ci: add support for django 3.2

[mariajgrimaldi]

Description
This PR supports Django 3.2 in CI as the Open edX community effort to give Django 3.2 support to all its dependencies. Here's the issue if you're interested.

[mariajgrimaldi]

Hi there @NarenderRajuB @marksweb @vinitkumar!
I'm tagging you in this issue as you're the latest contributors to the repo! Can you help me move this forward?

[marksweb]

Added a couple of minor requests to help the test suite going forwards.

[codecov-commenter]

Codecov Report

Merging #61 (b628fbe) into master (5ad9c1f) will not change coverage.
The diff coverage is n/a.

❗ Current head b628fbe differs from pull request most recent head b6f6b95. Consider uploading reports for the commit b6f6b95 to get more accurate results

@@           Coverage Diff           @@
##           master      #61   +/-   ##
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  Coverage   99.63%   99.63%           
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  Files           9        9           
  Lines         541      541           
  Branches       89       89           
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  Hits          539      539           
  Misses          1        1           
  Partials        1        1           

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[mariajgrimaldi]

Hey! @marksweb I followed your suggestions! Thank you

[marksweb]

@mariajgrimaldi fantastic, thank your for your contribution.

[mariajgrimaldi]

Great! Thank you @marksweb
I'm looking forward to the new release! :)

[marksweb]

@mariajgrimaldi I can't actually do releases but I've raised with the team the fact that this needs a 3.2 compatible release following these changes 👍

[natabene]

@marksweb Thanks so much for looking into this. Have you had any news from the team? Do you know what the ETA for the 3.2 compatible release is?

[NicolaiRidani]

Hi @natabene @mariajgrimaldi I just wanted to let you know that our contributor team is looking into this. You can find us in Slack in #release-management (you are welcome to join us by the way). I hope it will be released as soon as possible. But we still have to clarify a few things internally first.

About us: The django-cms project (and all other projects that are part of the django CMS Github organization) is officially supported by the non-profit django CMS Association. We are a group of volunteers (individuals, agencies, companies, universities, etc.) who want to keep django-cms (and its ecosystem) alive and take it to the next level. The project(s) is/are entirely community driven. So we rely on the power of the community. Everyone is welcome to join us. For more information, feel free to contact me at nicolai@django-cms.org or join us on Slack (link above). Thank you :)