Prepare for 10.7.0~pre1

[scpeters]

🎈 Release

Preparation for 10.7.0~pre1 release.

Comparison to 10.6.0: sdformat10_10.6.0...sdf10

Needed by gazebo-tooling/release-tools#600

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 ignition-release (as needed): Depend on libignition-cmake2-dev >= 2.10.0 gazebo-release/sdformat10-release#6

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-commenter]

Codecov Report

Merging #799 (6434263) into sdf10 (92d20d2) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##            sdf10     #799   +/-   ##
=======================================
  Coverage   88.30%   88.30%           
=======================================
  Files          66       66           
  Lines       10571    10571           
=======================================
  Hits         9335     9335           
  Misses       1236     1236           

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