Upgrade Django to 3.2

[replaceafill]

This sets django-upgrade in pre-commit to upgrade Django to 3.2. Python requirements have been upgraded to compatible versions too.

Two changes are worth highlighting:

• The custom main.models.BlobTextField used to represent some paths has been replaced with Django's BinaryField. Combining Django 3.2 TextField with the MySQL's longblob type like the custom field does is not possible anymore since Django writes (and overwrites) Python's binary representation to the database. Switching to BinaryField allow us to keep using the same MySQL type without requiring data migrations, and makes the binary-type nature of those fields explicit in the Python code.
• In Django 1.11 the compilemessages command didn't fail when it was not able to write *.mo files due to permissions. In Django 3.2 the command fails interrupting the Docker build. That's why this sets ownership of the locale/**/LC_MESSAGES directories to the archivematica user explicitly.

Depends on artefactual-labs/archivematica-acceptance-tests#185
Connected to archivematica/Issues#1279