fix for MacOs

[codecov[bot]]

Codecov Report

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

Project coverage is 64.28%. Comparing base (5ec1641) to head (b237979). Report is 4 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #74 +/- ## ======================================= Coverage 64.28% 64.28% ======================================= Files 8 8 Lines 504 504 ======================================= Hits 324 324 Misses 180 180 ``` | [Flag](https://app.codecov.io/gh/SupervisedStylometry/SuperStyl/pull/74/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=SupervisedStylometry) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/SupervisedStylometry/SuperStyl/pull/74/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=SupervisedStylometry) | `64.28% <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=SupervisedStylometry#carryforward-flags-in-the-pull-request-comment) to find out more.

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