ci: remove unused pre-commit env from tox.ini

[SiQube]

while playing around everywhere I found this dead code

[codecov[bot]]

Codecov Report

Patch and project coverage have no change.

Comparison is base (0e2cb61) 100.00% compared to head (f190db1) 100.00%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #564 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 49 49 Lines 2176 2176 Branches 536 536 ========================================= Hits 2176 2176 ```

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