Fix compatibility with protobuf v30 (cpp 6.30.0) - similar to gz-msgs… (backport #677)

[mergify]

Summary

Fix compatibility with protobuf v30 (cpp 6.30.0) - similar to gz-msgs #499

Checklist

• [ x] Signed all commits for DCO
• [ n/a] Added tests
• [ n/a] Updated documentation (as needed)
• [ n/a] Updated migration guide (as needed)
• [ n/a] 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.

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🎉 New feature

Closes #

Summary

Test it

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• 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.

🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸

➡️ Forward port

Port <FROM_BRANCH> to <TO_BRANCH>

Branch comparison: https://github.com/gazebosim//compare/<TO_BRANCH>...<FROM_BRANCH>

Note to maintainers: Remember to Merge with commit (not squash-merge or rebase)

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🎈 Release

Preparation for <X.Y.Z> release.

Comparison to <x.y.z>: https://github.com/gazebosim//compare/<LATEST_TAG_BRANCH>...<RELEASE_BRANCH>

Needed by <PR(s)>

Checklist

• Asked team if this is a good time for a release
• There are no changes to be ported from the previous major version
• No PRs targeted at this major version are close to getting in
• Bumped minor for new features, patch for bug fixes
• Updated changelog
• Updated migration guide (as needed)
• Link to PR updating dependency versions in appropriate repository in gazebo-release (as needed):

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.

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This is an automatic backport of pull request #677 done by [Mergify](https://mergify.com).

[scpeters]

this has a test failure, but fixes a broken build, so I think it should be merged