Drop python3.8 support and fix dependency issues

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (c27c7f1) 96.07% compared to head (8cb896f) 95.63%. Report is 9 commits behind head on development.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## development #218 +/- ## =============================================== - Coverage 96.07% 95.63% -0.44% =============================================== Files 168 168 Lines 6982 6972 -10 =============================================== - Hits 6708 6668 -40 - Misses 274 304 +30 ``` | [Flag](https://app.codecov.io/gh/frankkramer-lab/aucmedi/pull/218/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=frankkramer-lab) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/frankkramer-lab/aucmedi/pull/218/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=frankkramer-lab) | `95.63% <100.00%> (-0.44%)` | :arrow_down: | 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=frankkramer-lab#carryforward-flags-in-the-pull-request-comment) to find out more.

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[muellerdo]

Functional, push to dev.