Protobuf: Do not require version 3 do support Protobuf 4.23.2 (23.2)

[traversaro]

🎉 New feature

GzProtobuf: Do not require version 3 do support Protobuf 4.23.2 (23.2)

Summary

The motivation is similar to https://github.com/gazebosim/gz-msgs/pull/346 .

Test it

Install protobuf 23.2 and run the tests (I guess the only way to do it easily for now is to use conda-forge, see https://repology.org/project/protobuf/versions .

Checklist

• [x] Signed all commits for DCO
• [ ] Added tests
• [ ] Added example and/or tutorial
• [x] Updated documentation (as needed)
• [x] Updated migration guide (as needed)
• [x] Consider updating Python bindings (if the library has them)
• [x] codecheck passed (See contributing)
• [x] All tests passed (See test coverage)
• [ ] While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.