Fix running non-py checks on GitHub CI

[wRAR]

https://github.com/scrapinghub/dateparser/blob/master/.github/workflows/main.yml has an explicit tox -e py which causes all envs to just run the tests, including e.g. flake8 and twinecheck jobs.

[serhii73]

I close this issue as it is already fixed @wRAR
cc: @Gallaecio

[serhii73]

It was fixed in #1248