Bump django-crispy-forms to 2.0 (#61)

* Update test matrix

 - Add Python 3.12
 - Remove Django 2.2, 3.0 and 3.1
 - Add Django 4.1 and 4.2

* Make tests pass

* Upgrade Flake8, so that it works on Python 3.12 too

* Remove `|safe` filters

See #28

* Add tests for HTML escaping

.github/workflows/test.yml

@@ -28,7 +28,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python: ['3.8', '3.9', '3.10', '3.11']
+        python: ['3.8', '3.9', '3.10', '3.11', '3.12']
     steps:
       - uses: actions/checkout@v3
       - uses: actions/setup-python@v2