testing/py3-connexion: drop
We don't want packages to remain in testing indefinitely, and I don't personally use this package, nor do I know anyone else that does.
If someone does, please let me know :)
Henrik Riomar, the original contributor, mentioned they may begin using it at some point, but without a specific timeframe1 7 months ago. I'd be happy to add it back and maintain it when someone uses it.