Compatibility with Bazel 6

[parthea]

An error appears when using bazel 6.0.0 because this BUILD.bazel uses @bazel_tools//platforms which has been removed

ERROR: /usr/local/google/home/partheniou/.cache/bazel/_bazel_partheniou/158c73e91735c8bd1e202dd9acfefc6b/external/bazel_tools/platforms/BUILD:19:6: in alias rule @bazel_tools//platforms:x86_64: Constraints from @bazel_tools//platforms have been removed. Please use constraints from @platforms repository embedded in Bazel, or preferably declare dependency on https://github.com/bazelbuild/platforms. See https://github.com/bazelbuild/bazel/issues/8622 for details.
ERROR: /usr/local/google/home/partheniou/.cache/bazel/_bazel_partheniou/158c73e91735c8bd1e202dd9acfefc6b/external/bazel_tools/platforms/BUILD:19:6: Analysis of target '@bazel_tools//platforms:x86_64' failed
ERROR: /usr/local/google/home/partheniou/.cache/bazel/_bazel_partheniou/158c73e91735c8bd1e202dd9acfefc6b/external/com_google_protobuf/BUILD:513:10: While resolving toolchains for target @com_google_protobuf//:protoc: invalid registered toolchain '//:pandoc_toolchain_linux': 
ERROR: Analysis of target '//tests/integration:redis_update' failed; build aborted: 

[parthea]

There is also an old version of protobuf in the build rules which is not compatible with bazel 6.

I've confirmed the issue is not present with the latest protobuf version 3.21.12 which is what is used in googleapis/googleapis here:

gapic-generator-python/repositories.bzl

Lines 18 to 20 in b4d1c4b

	_protobuf_version = "3.19.2"
	_protobuf_sha256 = "9ceef0daf7e8be16cd99ac759271eb08021b53b1c7b6edd399953a76390234cd"
	_protobuf_version_in_link = "v{}".format(_protobuf_version)