Bump the minimum version of proto-plus to 1.22.3

[parthea]

I had to manually fix a google-cloud-python PR that had a comment looking like this:

proto-plus version 1.22.3 includes a fix to resolve an issue where marshal fails with cross api dependency.
https://github.com/googleapis/proto-plus-python/releases/tag/v1.22.3

With older versions of proto-plus, generated unit tests would fail with TypeError due to the issue mentioned above with marshal failing for cross api dependencies.

=================================== FAILURES ===================================
_________________________ test_list_crypto_keys_pager __________________________

transport_name = 'grpc'

    def test_list_crypto_keys_pager(transport_name: str = "grpc"):
        client = KeyDashboardServiceClient(
            credentials=ga_credentials.AnonymousCredentials,
            transport=transport_name,
        )
    
        # Mock the actual call within the gRPC stub, and fake the request.
        with mock.patch.object(type(client.transport.list_crypto_keys), "__call__") as call:
            # Set the response to a series of pages.
            call.side_effect = (
                key_dashboard_service.ListCryptoKeysResponse(
                    crypto_keys=[
                        resources.CryptoKey(),
                        resources.CryptoKey(),
                        resources.CryptoKey(),
                    ],
>                   next_page_token="abc",
                ),
                key_dashboard_service.ListCryptoKeysResponse(
                    crypto_keys=[],
                    next_page_token="def",
                ),
                key_dashboard_service.ListCryptoKeysResponse(
                    crypto_keys=[
                        resources.CryptoKey(),
                    ],
                    next_page_token="ghi",
                ),
                key_dashboard_service.ListCryptoKeysResponse(
                    crypto_keys=[
                        resources.CryptoKey(),
                        resources.CryptoKey(),
                    ],
                ),
                RuntimeError,
            )

tests/unit/gapic/kms_inventory_v1/test_key_dashboard_service.py:1001: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <[AttributeError('Unknown field for ListCryptoKeysResponse: _pb') raised in repr()] ListCryptoKeysResponse object at 0x7f144f26da10>
mapping = {'crypto_keys': [, , ], 'next_page_token': 'abc'}
ignore_unknown_fields = False
kwargs = {'crypto_keys': [, , ], 'next_page_token': 'abc'}
params = {'crypto_keys': [, , ], 'next_page_token': 'abc'}
marshal = <proto.marshal.marshal.Marshal object at 0x7f144f66b950>
key = 'next_page_token', value = 'abc', pb_value = 'abc'

    def __init__(
        self,
        mapping=None,
        *,
        ignore_unknown_fields=False,
        **kwargs,
    ):
        # We accept several things for `mapping`:
        #   * An instance of this class.
        #   * An instance of the underlying protobuf descriptor class.
        #   * A dict
        #   * Nothing (keyword arguments only).
        if mapping is None:
            if not kwargs:
                # Special fast path for empty construction.
                super().__setattr__("_pb", self._meta.pb())
                return
    
            mapping = kwargs
        elif isinstance(mapping, self._meta.pb):
            # Make a copy of the mapping.
            # This is a constructor for a new object, so users will assume
            # that it will not have side effects on the arguments being
            # passed in.
            #
            # The `wrap` method on the metaclass is the public API for taking
            # ownership of the passed in protobuf object.
            mapping = copy.deepcopy(mapping)
            if kwargs:
                mapping.MergeFrom(self._meta.pb(**kwargs))
    
            super().__setattr__("_pb", mapping)
            return
        elif isinstance(mapping, type(self)):
            # Just use the above logic on mapping's underlying pb.
            self.__init__(mapping=mapping._pb, **kwargs)
            return
        elif isinstance(mapping, collections.abc.Mapping):
            # Can't have side effects on mapping.
            mapping = copy.copy(mapping)
            # kwargs entries take priority for duplicate keys.
            mapping.update(kwargs)
        else:
            # Sanity check: Did we get something not a map? Error if so.
            raise TypeError(
                "Invalid constructor input for %s: %r"
                % (
                    self.__class__.__name__,
                    mapping,
                )
            )
    
        params = {}
        # Update the mapping to address any values that need to be
        # coerced.
        marshal = self._meta.marshal
        for key, value in mapping.items():
            (key, pb_type) = self._get_pb_type_from_key(key)
            if pb_type is None:
                if ignore_unknown_fields:
                    continue
    
                raise ValueError(
                    "Unknown field for {}: {}".format(self.__class__.__name__, key)
                )
    
            try:
                pb_value = marshal.to_proto(pb_type, value)
            except ValueError:
                # Underscores may be appended to field names
                # that collide with python or proto-plus keywords.
                # In case a key only exists with a `_` suffix, coerce the key
                # to include the `_` suffix. It's not possible to
                # natively define the same field with a trailing underscore in protobuf.
                # See related issue
                # https://github.com/googleapis/python-api-core/issues/227
                if isinstance(value, dict):
                    if _upb:
                        # In UPB, pb_type is MessageMeta which doesn't expose attrs like it used to in Python/CPP.
                        keys_to_update = [
                            item
                            for item in value
                            if item not in pb_type.DESCRIPTOR.fields_by_name
                            and f"{item}_" in pb_type.DESCRIPTOR.fields_by_name
                        ]
                    else:
                        keys_to_update = [
                            item
                            for item in value
                            if not hasattr(pb_type, item)
                            and hasattr(pb_type, f"{item}_")
                        ]
                    for item in keys_to_update:
                        value[f"{item}_"] = value.pop(item)
    
                pb_value = marshal.to_proto(pb_type, value)
    
            if pb_value is not None:
                params[key] = pb_value
    
        # Create the internal protocol buffer.
>       super().__setattr__("_pb", self._meta.pb(**params))
E       TypeError: Parameter to MergeFrom() must be instance of same class: expected google.cloud.kms.v1.CryptoKey got CryptoKey.

.nox/unit-3-7/lib/python3.7/site-packages/proto/message.py:599: TypeError