Fixed stray quote in install.ps1 PowerShell script for Windows.

[drolenc]

Summary of changes

The stray quote was causing a PowerShell error in the install/upgrade/downgrade
commands for Windows.

I'll review the commits, so I mostly want to understand the "why" rather than the "what"

Checklist

• [ x] New functions have typespecs, changed functions were updated
• [ x] Same for documentation, including moduledocs
• [ x] Tests were added or updated to cover changes
• [ x] Commits were squashed into a single coherent commit

Licensing/Copyright

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