Fix MetaDrive dependency for 3.1.0 release

[lola831]

Description

Reverts the MetaDrive extra to a version-based PyPI dependency, gates MetaDrive under test-full on Python 3.12+, and updates the docs with installation notes (Python 3.12+, macOS 3D, braking), and adjusts MetaDrive tests to xfail the 0.4.3 braking/handbrake issue.

Issue Link

Checklist

• I have tested the changes locally via pytest and/or other means
• I have added or updated relevant documentation
• I have autoformatted the code with black and isort
• I have added test cases (if applicable)

Additional Notes

[dfremont]

Looks good, just a couple minor comments above.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.02%. Comparing base (8a2081a) to head (6765a14).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #431      +/-   ##
==========================================
+ Coverage   89.91%   90.02%   +0.11%     
==========================================
  Files          54       54              
  Lines       13578    13585       +7     
==========================================
+ Hits        12208    12230      +22     
+ Misses       1370     1355      -15     

see 8 files with indirect coverage changes

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