Prepare for 8.0.0~pre2 Release

[azeey]

🎈 Release

Preparation for 8.0.0~pre2 release.

Comparison to 7.3.0: gz-sensors7_7.3.0...gz-sensors8

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 #388 (970afe7) into gz-sensors8 (f48aab8) will not change coverage.
The diff coverage is n/a.

❗ Current head 970afe7 differs from pull request most recent head fb0b02f. Consider uploading reports for the commit fb0b02f to get more accurate results

@@             Coverage Diff              @@
##           gz-sensors8     #388   +/-   ##
============================================
  Coverage        72.78%   72.78%           
============================================
  Files               36       36           
  Lines             4972     4972           
============================================
  Hits              3619     3619           
  Misses            1353     1353