Mypy checks with enums

[havogt]

I create this issue to reference from gt4py comments.

@enum.unique
class MyEnum(eve.IntEnum):
    member: 0

reveal(MyEnum.member) # <- int but should be MyEnum

Run this in outside of the eve package (maybe problem also inside?).

@egparedes and I couldn't figure out what's going on, in a short debugging session, but we stopped as it should go away in the next refactoring.