Remove dead code and manage dependencies with poetry

[42nick]

• Remove unused files.
• Manage test-dependencies via poetry.

NOTE: The huge diff in the poetry.lock is a result of orion and kaleido.

[codecov[bot]]

Codecov Report

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

Project coverage is 87.06%. Comparing base (a211721) to head (74c45bd). Report is 1 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #330 +/- ## ========================================== + Coverage 86.46% 87.06% +0.59% ========================================== Files 34 34 Lines 4538 4538 ========================================== + Hits 3924 3951 +27 + Misses 614 587 -27 ```

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