Update dependencies for 2022-08

Closes #60 (closed)

This MR updates the dependencies of the python code. However it doesn't update to django 4.1, as this is not supported by djangorestframework-jsonapi 5.0.0:

The conflict is caused by:
    The user requested Django==4.1
    django-cors-headers 3.13.0 depends on Django>=3.2
    django-debug-toolbar 3.6.0 depends on Django>=3.2.4
    django-filter 22.1 depends on Django>=3.2
    django-jazzmin 2.5.0 depends on django>=2.2
    django-polymorphic 3.1.0 depends on Django>=2.1
    djangorestframework 3.13.1 depends on django>=2.2
    djangorestframework-jsonapi 5.0.0 depends on django<4.1 and >=2.2

Unfortunally this is currently the latest version of djangorestframework-jsonapi & we rely on it...