Fix the labeler configuration example

[llucax]

The labeler configuration example was using a wrong key, it should be all-globs-to-all-files instead of all-glob-to-all-file.

Note we use perl instead of sed in the migration script because it is more portable and we don't need to worry about the differences between the different sed implementations (refs #302).

[llucax]

Skipping release notes because it is too minor to be mentioned.

[llucax]

Something funny is going on with the test, google protobuf complains about not being able to import something. WTF.

[llucax]

We are getting this:

UserWarning: Protobuf gencode version 5.27.2 is older than the runtime version 5.28.0 at frequenz/api/test/test.proto."

And then some internal import error. It is super weird because we are installing everything from scratch in the test, so there should be no version mismatch.

I found this issue:

• Unable to run Python example code acc. "quick start" due to version check grpc/grpc#37610

But I guess that one could be really a version mismatch because the example code is provided pre-generated.

[llucax]

I could reproduce locally.

[llucax]

This might be something to do with dependencies interactions:

Because googleapis-common-protos==1.56.2 depends on protobuf>=3.15.0,<4.0.0.dev0 and you require googleapis-common-protos==1.56.2, we can conclude that you require protobuf>=3.15.0,<4.0.0.dev0.
      And because you require protobuf==4.25.3, we can conclude that the requirements are unsatisfiable.