feat: add `pydocstyle`

[JaeAeich]

related to - #177

[codecov[bot]]

Codecov Report

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

Project coverage is 98.21%. Comparing base (b313375) to head (c1dffd0).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #186 +/- ## ======================================= Coverage 98.21% 98.21% ======================================= Files 8 8 Lines 559 559 ======================================= Hits 549 549 Misses 10 10 ``` | [Flag](https://app.codecov.io/gh/elixir-cloud-aai/TESK/pull/186/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-cloud-aai) | Coverage Δ | | |---|---|---| | [test_unit](https://app.codecov.io/gh/elixir-cloud-aai/TESK/pull/186/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-cloud-aai) | `98.21% <ø> (ø)` | | 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=elixir-cloud-aai#carryforward-flags-in-the-pull-request-comment) to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.