Test using recent django and python versions and fix docker deploy

[codecov[bot]]

Codecov Report

Base: 73.73% // Head: 73.76% // Increases project coverage by +0.02% :tada:

Coverage data is based on head (2168596) compared to base (141beca). Patch has no changes to coverable lines.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #143 +/- ## ========================================== + Coverage 73.73% 73.76% +0.02% ========================================== Files 38 38 Lines 1854 1856 +2 ========================================== + Hits 1367 1369 +2 Misses 487 487 ``` | [Impacted Files](https://codecov.io/gh/agstrike/silverstrike/pull/143?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=agstrike) | Coverage Δ | | |---|---|---| | [silverstrike/models/recurrence.py](https://codecov.io/gh/agstrike/silverstrike/pull/143/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=agstrike#diff-c2lsdmVyc3RyaWtlL21vZGVscy9yZWN1cnJlbmNlLnB5) | `85.03% <0.00%> (+0.23%)` | :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=agstrike). 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=agstrike)

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