Update Django to 3.2 and other Python dependencies (#1286)

[ssciolla]

The PR aims to resolve #1084 and #1286.

I've built with these changes, and everything seems to work so far. I will be looking more closely at each updated dependency to see where it is used, what has changed, and whether I need to do anything special to test it. Any assistance with testing would be appreciated.

To do

• Scan dependencies and update if possible
  • Find libraries with new releases using PyPi, and update requirements.txt
  • Update webpack-bundle-tracker npm package to ensure compatibility with django-webpack-loader
  • Execute npm install in repository to update package-lock.json
  • Remove outdated and/or minimally used dependencies, including django-settings-export, django-model-utils, and django-macros.
  • Fix bugs associated with updates to Django, pinax-eventlog, and pandas.
• Fix Django warnings
  • Specify DEFAULT_AUTO_FIELD
  • Replace NullBooleanField usage

Testing

• Run with and without LTI
• Review logs associated with each view and try functionality
• Run cron with a few different courses
• Run management commands

[ssciolla]

I think this is ready for review and further testing. Please let me know if you have any other questions. Issue #1286 has a lot of notes and linked resources about the dependency changes.

[jonespm]

A couple of comments, I think this is good to get in and we can create new issues if needed for the createkeys and the roles change (if there isn't one for that yet)

[ssciolla]

@zqian and @pushyamig, do either of you plan to or want to review this before it's merged?

[pushyamig]

@ssciolla please go ahead and merge it if you like