Upgrade Django to v4 and upgrade other python dependencies

[dchiller]

Dependency changes: Upgrade to Django 4

The main impetus behind this PR was to close #743. As such, the following dependencies were changed pursuant to upgrading to django 4:

• Bump django from 3.2.19 to 4.2.2 (latest patch of LTS version)
  • Support for python 3.6 was dropped in django 4. django 4 requires a minimum of python 3.8. All containers where python is installed now use > 3.8.
  • django-extensions supports django 4 starting with django-extensions 3.2. This PR includes the latest patch at django-extensions 3.2.3 (also the latest version).
  • djangorestframework added support for django 4.1 with djangorestframework 3.14. djangorestframework 3.14 is also working with django 4.2.
  • Django support for psycopg2 is likely to be deprecated in the future. Django 4 documentation suggests moving to psycopg. This PR goes ahead and makes that switch by removing psycopg2 and adding psycopg 3.1.8. This upgrade required changing the ENGINE option for the database in settings.py.
• Bump python from 3.6.9 to 3.10.12. A minimum of python 3.8 is required for django 4; however, upgrade to 3.10 is possible with no additional dependency considerations.
  • coverage became compatible with python 3.8 with coverage >= 5.
  • With the required update to python 3.8, pip raised an dependency conflict error between celery (at 5.1.2) and django-celery-results (at 2.4.0). Upgrading celery >= 5.2 (the most recent version is at 5.3.1) solved the issue.

Additional upgrades

The following additional dependency upgrades are made to take advantage of package fixes and patches:

• celery: 5.2.0 -> 5.3.1
• Markdown: 2.6.2 -> 3.4.3
• requests: 2.20.0 -> 2.31.0
• coverage: 5.0.0 -> 7.2.7
• django-celery-results: 2.4.0 -> 2.5.1
• Werkzeug: 2.0.3 -> 2.3.6

An upgrade to solrpy is available, but results in unexpected output. Cantus Ultimus's used of solrpy already has some issues an inconsistencies, so this PR leaves that to a later time.