Relax protobuf pinnings.

[bdice]

Description

This PR relaxes cudf's protobuf pinnings to help with compatibility issues. cudf uses protobuf in two places.

The first place protobuf is used is at build time, to generate a Python module from a .proto file in python/cudf/cmake/Modules/ProtobufHelpers.cmake:

cudf/python/cudf/cmake/Modules/ProtobufHelpers.cmake

Lines 16 to 17 in f8e5a89

	# Compile protobuf files to Python. All arguments are assumed to be .proto files.
	function(codegen_protoc)

The second place protobuf is used is in the generated file python/cudf/cudf/utils/metadata/orc_column_statistics_pb2.py which is imported here.

The generated Python module used at runtime should be compatible with newer versions of protobuf than the version used to build the Python module, from my understanding of https://protobuf.dev/support/cross-version-runtime-guarantee/. Therefore, we only require that the runtime pinning of protobuf is of the same major version and an equal-or-greater minor version. That allows us to relax this pinning.

Follow-up to #12864, see that PR for more context.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[raydouglass]

Should technically be <5.0.0a0 (I think the minor & patch might be required) to prevent pre-release versions, but it is unlikely that conda-forge will upload a pre-release, so I will approve.

[vyasr]

/merge