Add py.typed marker and stub for decorator type

[ronyb29]

Hey nice lib,

I'm trying to make it "mypy-friendly".

tested on py3.11 with this stub, but it should work for older versions too

from memoize.configuration import DefaultInMemoryCacheConfiguration
from memoize.wrapper import memoize


@memoize(configuration=DefaultInMemoryCacheConfiguration())
async def get_value(arg: str, *, kwarg: str = None) -> str:
    return arg + (kwarg or '')

reveal_type(get_value)

before would yield

checktypes.py:9: note: Revealed type is "Any"

now yields

checktypes.py:9: note: Revealed type is "def (arg: builtins.str, *, kwarg: Union[builtins.str, None] =) -> typing.Coroutine[Any, Any, builtins.str]"

[kwarunek]

configuration and invalidation are optional and should be marked accordingly (Optional from typing).