GH Actions: disable all AutoDJ tests on Windows

[Be-ing]

Different tests are failing on different builds. I do not know why
they work on Ubuntu and macOS but not Windows.

For example:
https://github.com/mixxxdj/mixxx/runs/1448847307

 The following tests FAILED:
	 10 - AutoDJProcessorTest.FadeAtOutroStart_LongerIntro (Failed)
	 21 - AutoDJProcessorTest.EnabledSuccess_PlayingDeck2_TrackLoadFailed (Failed)

https://github.com/mixxxdj/mixxx/runs/1448857108

The following tests FAILED:
	 10 - AutoDJProcessorTest.FadeAtOutroStart_LongerIntro (Failed)
	 21 - AutoDJProcessorTest.EnabledSuccess_PlayingDeck2_TrackLoadFailed (Failed)

https://github.com/mixxxdj/mixxx/runs/1448901972
This build initially worked, then I manually restarted it to test if clcache works (it does not).

 The following tests FAILED:
	 10 - AutoDJProcessorTest.FadeAtOutroStart_LongerIntro (Failed)

https://github.com/Be-ing/mixxx/runs/1450027225

The following tests FAILED:
	 15 - AutoDJProcessorTest.EnabledSuccess_DecksStopped_TrackLoadFails (Failed)
	 18 - AutoDJProcessorTest.EnabledSuccess_PlayingDeck1_TrackLoadFailed (Failed)

[uklotzde]

These test (or the code?) can only be analyzed and fixed locally. LGTM

[Be-ing]

These tests weren't failing on AppVeyor or Jenkins though... or were they?

[uklotzde]

None that I am aware of. Maybe an issue with VS 2019 vs. VS 2017?

[Be-ing]

That is plausible.

[Holzhaus]

No, these also happened with windows-2016 where VS 2017 is installed.