Fix PyInstaller Packaging Issues

[danyeaw]

This PR fixes three issues with PyInstaller:

1. GTK started linking to HarfBuzz with Gtk and Pango. I added a hook to work around this until a new version of PyInstaller is released, the original issue is at GTK in Windows: Typelib for HarfBuzz version '0.0' is not found pyinstaller/pyinstaller#5129
2. Although the tinycss2 hook is now integrated with the pyinstaller-hooks-contrib package, we aren't yet using PyInstaller 4.0 because of a separate issue. I added back in this hook for us. Tinycss2 is also working on a new release which will get rid of the need for a hook at all.
3. Windows MSYS2 uses an older version of setuptools which has an issue around use of py2.warn.

PR Checklist

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PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Documentation content changes

What is the current behavior?

Windows packages won't launch

Issue Number: N/A

What is the new behavior?

They launch now

Does this PR introduce a breaking change?

• Yes
• No

Other information