`types.CoroutineType.cr_frame` should be `FrameType | None`

[Zac-HD]

typeshed/stdlib/types.pyi

Lines 461 to 462 in 0e9b8c9

	@property
	def cr_frame(self) -> FrameType: ...

also GeneratorType.gi_frame and AsyncGeneratorType.ag_frame, cf python/cpython#112428; possibly others I don't know of.

motivation: python-trio/trio#3338