XBlock 3.0.0: Collapse Extraneous XBlock Mixins

What's Changed

Important (see CHANGELOG.rst for details):

• feat!: collapse extraneous XBlock mixins by @kdmccormick in #718

Unimportant:

• Python Requirements Update by @edx-requirements-bot in #723
• Running tests using python 3.12 by @salman2013 in #724
• Python Requirements Update by @edx-requirements-bot in #725
• Unpin the Django dependency by @feanil in #726
• Python Requirements Update by @edx-requirements-bot in #728

New Contributors

• @salman2013 made their first contribution in #724

Full Changelog: 2.0.0...3.0.0