Update django support

[hramezani]

Fixes #

Description of the Change

• Remove Django 3.0 support
• Add Django 3.2 support
• Add Python and Django supported versions badges to README

Checklist

• PR only contains one change (considered splitting up PR)
• unit-test added
• documentation updated
• CHANGELOG.md updated (only for user relevant changes)
• author name in AUTHORS

[codecov]

Codecov Report

Merging #968 (d2862e3) into master (e5ecd56) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #968   +/-   ##
=======================================
  Coverage   96.62%   96.62%           
=======================================
  Files          31       31           
  Lines        1716     1716           
=======================================
  Hits         1658     1658           
  Misses         58       58           

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