Make `assert_type` use `ReifiedGeneric` so that it can check at runtime

[github-actions]

Make assert_type use ReifiedGeneric so that it can check at runtime.

basedtyping/basedtyping/typetime_only.py

Line 24 in 997af52

# TODO: make this use ReifiedGeneric so that it can check at runtime

class assert_type(Generic[T]):
    """Used to assert that a value is type ``T``.

    note: This is more like a function than a class,
    but it's defined as a class so that you can explicitly specify the generic.
    """

    # TODO: make this use ReifiedGeneric so that it can check at runtime
    # None return type on __new__ is supported in pyright but not mypy
    def __new__(cls, _value: T) -> None:  # type: ignore[misc]
        pass

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