Return type of save method is partially unknown

[dantownsend]

Every few months it seems like pyright gets stricter and detects more type errors.

This is partially ambiguous:

piccolo/piccolo/table.py

Line 472 in 8fd69e7

) -> t.Union[Insert, Update]:

Because Insert and Update use generics to specify which table it's being performed on. So instead of Insert, it should be Insert[TableInstance], or something like that.

We have ./scripts/pyright.sh for testing this.