Prepare for 7.4.0 release

[iche033]

🎈 Release

Preparation for 7.4.0 release.

Comparison to 7.3.1: gz-rendering7_7.3.1...prep_7.4.0

Needed by gazebosim/gz-sim#1979

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 #849 (b41163b) into gz-rendering7 (a14b582) will decrease coverage by 0.01%.
The diff coverage is n/a.

❗ Current head b41163b differs from pull request most recent head 1284ddd. Consider uploading reports for the commit 1284ddd to get more accurate results

@@                Coverage Diff                @@
##           gz-rendering7     #849      +/-   ##
=================================================
- Coverage          77.14%   77.14%   -0.01%     
=================================================
  Files                170      170              
  Lines              14716    14716              
=================================================
- Hits               11353    11352       -1     
- Misses              3363     3364       +1     

see 1 file with indirect coverage changes