Prepare for 8.0.0 Release

[azeey]

🎈 Release

Preparation for 8.0.0 release.

Comparison to 8.0.0-pre3: gz-rendering8_8.0.0-pre3...gz-rendering8

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]

Codecov Report

Merging #926 (626b541) into gz-rendering8 (d3807fe) will not change coverage.
The diff coverage is n/a.

❗ Current head 626b541 differs from pull request most recent head 244fafa. Consider uploading reports for the commit 244fafa to get more accurate results

@@              Coverage Diff               @@
##           gz-rendering8     #926   +/-   ##
==============================================
  Coverage          75.15%   75.15%           
==============================================
  Files                177      177           
  Lines              16830    16830           
==============================================
  Hits               12649    12649           
  Misses              4181     4181