Remove Tests on Python 3.7

[adtzlr]

closes #53

[codecov[bot]]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (440347e) 89.77% compared to head (59f8af8) 89.77%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #54 +/- ## ======================================= Coverage 89.77% 89.77% ======================================= Files 27 27 Lines 1242 1242 ======================================= Hits 1115 1115 Misses 127 127 ``` | [Files Changed](https://app.codecov.io/gh/adtzlr/trusspy/pull/54?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Andreas+Dutzler) | Coverage Δ | | |---|---|---| | [src/trusspy/\_\_about\_\_.py](https://app.codecov.io/gh/adtzlr/trusspy/pull/54?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Andreas+Dutzler#diff-c3JjL3RydXNzcHkvX19hYm91dF9fLnB5) | `100.00% <100.00%> (ø)` | |

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