mamageprojects updates + update requirements

[jedie]

• Remove Django 4.1 tests and add 5.0
• Remove Python 3.9 from test matrix (because Django 5.0 doesn't support it)
• Use pretty_repr from rich in CompareObject
• Modernize CSS styles and support dark theme
• Add JSONField to VariantModel test model

[codecov[bot]]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (85d5c85) 79.82% compared to head (f6ba3ed) 80.07%.

Files	Patch %	Lines
manage.py	33.33%	2 Missing :warning:
reversion_compare/mixins.py	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #227 +/- ## ========================================== + Coverage 79.82% 80.07% +0.24% ========================================== Files 38 38 Lines 1378 1385 +7 Branches 200 202 +2 ========================================== + Hits 1100 1109 +9 + Misses 278 276 -2 ```

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