Build sdist and wheel in GitHub Actions

[altendky]

WIP for:

• Should probably be a tox env
• Get some identification into the file name
• Get at least the same identification into the .zip itself

[codecov]

Codecov Report

Merging #91 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master    #91   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           6      6           
  Lines         446    446           
  Branches       69     69           
=====================================
  Hits          446    446

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