bump/django 3.2

[EricTRL]

Django 2.2 reached its end of life in April 2022, so upgrading to the next LTS should've been done sooner than later. This PR shows progress towards an upgrade to Django 3.2 LTS.

While we're at it, this also upgrades almost all used packages, which were not actively supporting Django 2.2 either anymore.

Some other notable things to look at:

• [x] Check how Martor's CSS/JS interacts with the changes to the way the Django admin panel loads css/js. We might be able to simplify logic since these two were conflicting earlier on. Things still suck, mostly because of conflicts between jQuery/Bootstrap versions of Squire (bootstrap4) and Martor (bootstrap5)
• [x] Verify that markdown is still rendered properly in the frontend when making changes to the above.
• [x] Likewise, verify that the recurrence widget from django-recurrence still works properly in the admin panel, as this previously relied on some admin js/css. Seems to work fine.
• [x] See if django-recurrences fixes its previous issues when working with DST. There's a lot of logic in Squire's code to work around that, and removing it simplifies things a lot. It does not.
• [x] Check whether django-ical introduced support for RECURRENCE_ID, which is currently manually patched in. It does not.

[codecov[bot]]

Codecov Report

Base: 95.40% // Head: 95.45% // Increases project coverage by +0.04% :tada:

Coverage data is based on head (28b1804) compared to base (fcc9ece). Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #282 +/- ## ========================================== + Coverage 95.40% 95.45% +0.04% ========================================== Files 115 115 Lines 4769 4771 +2 Branches 465 756 +291 ========================================== + Hits 4550 4554 +4 + Misses 150 148 -2 Partials 69 69 ``` | Flag | Coverage Δ | | |---|---|---| | unittests | `95.45% <100.00%> (+0.04%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=esrg-knights#carryforward-flags-in-the-pull-request-comment) to find out more. | [Impacted Files](https://codecov.io/gh/esrg-knights/Squire/pull/282?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=esrg-knights) | Coverage Δ | | |---|---|---| | [activity\_calendar/admin.py](https://codecov.io/gh/esrg-knights/Squire/pull/282/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=esrg-knights#diff-YWN0aXZpdHlfY2FsZW5kYXIvYWRtaW4ucHk=) | `90.21% <ø> (ø)` | | | [core/widgets.py](https://codecov.io/gh/esrg-knights/Squire/pull/282/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=esrg-knights#diff-Y29yZS93aWRnZXRzLnB5) | `100.00% <ø> (ø)` | | | [inventory/admin.py](https://codecov.io/gh/esrg-knights/Squire/pull/282/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=esrg-knights#diff-aW52ZW50b3J5L2FkbWluLnB5) | `94.23% <ø> (-0.11%)` | :arrow_down: | | [inventory/committee\_pages/config.py](https://codecov.io/gh/esrg-knights/Squire/pull/282/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=esrg-knights#diff-aW52ZW50b3J5L2NvbW1pdHRlZV9wYWdlcy9jb25maWcucHk=) | `94.44% <ø> (ø)` | | | [core/admin.py](https://codecov.io/gh/esrg-knights/Squire/pull/282/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=esrg-knights#diff-Y29yZS9hZG1pbi5weQ==) | `93.57% <100.00%> (-0.12%)` | :arrow_down: | | [core/models.py](https://codecov.io/gh/esrg-knights/Squire/pull/282/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=esrg-knights#diff-Y29yZS9tb2RlbHMucHk=) | `96.36% <100.00%> (ø)` | | | [membership\_file/admin.py](https://codecov.io/gh/esrg-knights/Squire/pull/282/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=esrg-knights#diff-bWVtYmVyc2hpcF9maWxlL2FkbWluLnB5) | `98.21% <100.00%> (ø)` | | | [squire/settings.py](https://codecov.io/gh/esrg-knights/Squire/pull/282/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=esrg-knights#diff-c3F1aXJlL3NldHRpbmdzLnB5) | `100.00% <100.00%> (ø)` | | | [squire/urls.py](https://codecov.io/gh/esrg-knights/Squire/pull/282/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=esrg-knights#diff-c3F1aXJlL3VybHMucHk=) | `100.00% <100.00%> (ø)` | | | [squire/util.py](https://codecov.io/gh/esrg-knights/Squire/pull/282/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=esrg-knights#diff-c3F1aXJlL3V0aWwucHk=) | `100.00% <0.00%> (+11.76%)` | :arrow_up: | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=esrg-knights). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=esrg-knights)

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