Re-introduce vcpython27 in GitHub Actions

[sajith]

Fix for 3537.

I broke the CI when I merged #862: Turns out that netifaces has not published a .whl package for Python 2.7 and 64-bit Windows, so we will need vcpython27 after all. PR branch for #862 was older than from the time netifaces was added, so I missed it when testing.

Sorry. :-(

[sajith]

Related issue: al45tair/netifaces/issues/47

[codecov]

Codecov Report

Merging #909 (c8aab08) into master (4e5eb13) will decrease coverage by 0%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #909    +/-   ##
=======================================
- Coverage      92%     91%    -0%     
=======================================
  Files         158     158            
  Lines       27609   27609            
  Branches     4136    3933   -203     
=======================================
- Hits        25306   25261    -45     
+ Misses       1636    1575    -61     
- Partials      667     773   +106     

Impacted Files	Coverage Δ
src/allmydata/util/dictutil.py	79% <0%> (-21%)	⬇️
src/allmydata/util/humanreadable.py	65% <0%> (-16%)	⬇️
src/allmydata/_monkeypatch.py	86% <0%> (-14%)	⬇️
src/allmydata/crypto/__init__.py	86% <0%> (-14%)	⬇️
src/allmydata/immutable/downloader/__init__.py	86% <0%> (-14%)	⬇️
src/allmydata/storage/common.py	88% <0%> (-12%)	⬇️
src/allmydata/crypto/error.py	89% <0%> (-11%)	⬇️
src/allmydata/util/_python3.py	89% <0%> (-11%)	⬇️
src/allmydata/util/assertutil.py	89% <0%> (-11%)	⬇️
src/allmydata/crypto/util.py	92% <0%> (-8%)	⬇️
... and 77 more

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[exarkun]

Thanks. Sorry I didn't catch this one in review! Please merge.