Determine if grpcio-gcp is still needed in extras

[parthea]

grpcio-gcp is listed under extras in setup.py. The package doesn't support protobuf 4.21.0. The package has not been updated since 2018. This issue is to track whether this extra is still required.

python-api-core/setup.py

Line 39 in e92045b

"grpcgcp": "grpcio-gcp >= 0.2.2, < 1.0dev",

See stack trace below and build log here.

________________ ERROR collecting tests/unit/test__dataframe.py ________________
tests/unit/test__dataframe.py:22: in <module>
    from google.cloud import monitoring_v3
google/cloud/monitoring_v3/__init__.py:17: in <module>
    from .services.alert_policy_service import AlertPolicyServiceClient
google/cloud/monitoring_v3/services/alert_policy_service/__init__.py:16: in <module>
    from .client import AlertPolicyServiceClient
google/cloud/monitoring_v3/services/alert_policy_service/client.py:24: in <module>
    from google.api_core import gapic_v1
.nox/prerelease_deps-3-8/lib/python3.8/site-packages/google/api_core/gapic_v1/__init__.py:18: in <module>
    from google.api_core.gapic_v1 import method
.nox/prerelease_deps-3-8/lib/python3.8/site-packages/google/api_core/gapic_v1/method.py:24: in <module>
    from google.api_core import grpc_helpers
.nox/prerelease_deps-3-8/lib/python3.8/site-packages/google/api_core/grpc_helpers.py:29: in <module>
    import grpc_gcp
.nox/prerelease_deps-3-8/lib/python3.8/site-packages/grpc_gcp/__init__.py:16: in <module>
    from grpc_gcp import _channel
.nox/prerelease_deps-3-8/lib/python3.8/site-packages/grpc_gcp/_channel.py:19: in <module>
    from grpc_gcp.proto import grpc_gcp_pb2
.nox/prerelease_deps-3-8/lib/python3.8/site-packages/grpc_gcp/proto/grpc_gcp_pb2.py:33: in <module>
    _descriptor.EnumValueDescriptor(
.nox/prerelease_deps-3-8/lib/python3.8/site-packages/google/protobuf/descriptor.py:755: in __new__
    _message.Message._CheckCalledFromGeneratedFile()
E   TypeError: Descriptors cannot not be created directly.
E   If this call came from a _pb2.py file, your generated code is out of date and must be regenerated with protoc >= 3.19.0.
E   If you cannot immediately regenerate your protos, some other possible workarounds are:
E    1. Downgrade the protobuf package to 3.20.x or lower.
E    2. Set PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION=python (but this will use pure-Python parsing and will be much slower).