Test on Windows OS.

[delucchi-cmu]

Now that we don't depend on healpy, everything should run well on Windows. This adds a test to confirm that.

See astronomy-commons/hats#440

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.55%. Comparing base (f65d2e9) to head (dbe2e6c).
Report is 36 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #454   +/-   ##
=======================================
  Coverage   94.55%   94.55%           
=======================================
  Files          28       28           
  Lines        1615     1615           
=======================================
  Hits         1527     1527           
  Misses         88       88           

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