Prepare for 8.2.0 Release

[azeey]

🎈 Release

Preparation for 8.2.0 release.

Comparison to 8.1.0: https://github.com/gazebosim/gz-sim/compare/gz-sim8_8.1.0...gz-sim8

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.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 65.95%. Comparing base (b482a2d) to head (c5b41c8).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## gz-sim8 #2335 +/- ## =========================================== - Coverage 65.95% 65.95% -0.01% =========================================== Files 327 327 Lines 31347 31347 =========================================== - Hits 20676 20675 -1 - Misses 10671 10672 +1 ```

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