Minor CI updates

[CasperWA]

Changes:

• Rename deps_static to pytest.
• Run adapters tests for any Python version except 3.7 (see AiiDA tests only run on Python 3.8 in CI #401 for more info).
• Run pytest for all tests with and without a real MongoDB.
  The old CI doesn't make sense anymore, since we no longer distinguish between "regular" and "index" servers. This is rather done directly in the tests themselves where needed.
• Use v1 for CasperWA/push-protected action.
• Use high verbosity for all pytest runs, i.e., add a -vvv option.

[codecov]

Codecov Report

Merging #422 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #422   +/-   ##
=======================================
  Coverage   90.99%   90.99%           
=======================================
  Files          55       55           
  Lines        2522     2522           
=======================================
  Hits         2295     2295           
  Misses        227      227           

Flag	Coverage Δ
#unittests	90.99% <ø> (ø)

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[ml-evs]

LGTM!