Remove installing PowerShell in cibuild, this is no longer needed

[bkoelman]

All GitHub Actions runners now come preinstalled with a PowerShell version that is high enough to generate our documentation.

QUALITY CHECKLIST

• Changes implemented in code
• Complies with our contributing guidelines
• N/A: Adapted tests
• N/A: Documentation updated

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.83%. Comparing base (4e0f2a7) to head (8b0b90b).
Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1563   +/-   ##
=======================================
  Coverage   90.83%   90.83%           
=======================================
  Files         348      348           
  Lines       11158    11158           
  Branches     1828     1828           
=======================================
  Hits        10135    10135           
  Misses        673      673           
  Partials      350      350           

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