Formula installer req satisfied

Fixes #31471 and #30901.

Problem with pyqt5 was because we already had scheduled ```#<Dependency: "python3" [:recommended]>``` and ```sip``` was providing us with ```#<Python3Dependency: "python3" [:optional]>```.

I don't know if this is a correct fix for this, but it works in both cases.
That all working now? If so I'm happy for @jacknagel to merge this tonight or I'll merge tomorrow. Thanks so much for your work on this!