GitHub Actions not running devs

[fgrunewald]

@pckroon I think that also here in martinize2 github actions is not installing the dev packages but rather running on the latest python version. If you could quickly check then I'll raise an issue.

[pckroon]

Run actions/setup-python@v2
  with:
    python-version: 3.7-dev
    token: ***
  env:
    VERMOUTH_TEST_DSSP: mkdssp
    SKIP_GENERATE_AUTHORS: 1
    SKIP_WRITE_GIT_CHANGELOG: 1
Successfully setup CPython (3.9.6)

Indeed. non-dev (e.g. python-3.7) does work as intended though.

[fgrunewald]

this has been resolved