2.3.1

• Upgraded to Django 2.2.16
  Fixes Django vulnerabilities:
  • http://nvd.nist.gov/nvd.cfm?cvename=CVE-2020-24583
  • http://nvd.nist.gov/nvd.cfm?cvename=CVE-2020-24584
• Updated lxml to 4.5.2
• Updated jsonschema to 3.2.0
• Updated django-test-migrations to 1.0.0