• [html] Remove old flat-theme body class.
• [html] Remove type="text/css" and type="text/javascript" attributes.
• [css] Fix filter input fields collapsing on different layouts. #338
• [css] Fix paginator buttons height.
• [css] Fix foldable-apps +/- button vertical alignment.
• [css] Split admin-interface-fix.css CSS file into multiple files for easier debugging.
• [css] Rename form-controls.css to sticky-form-controls.css.
• [css] Move third-party compatibility CSS files to a third-party folder.
• [css] Move related-modal.css to related-modal plugin folder.
• [third-party] Update compatibility with django-streamfield.
• [ci] Replace Black and isort with Ruff-format.
• [ci] Bump pre-commit hooks.