Add support for py.typed file

[nzsmith1]

Resolves #194

I have added the py.typed file to the project and added it to the pyproject.toml file. Running a test file:

from beanie import Document

class test(Document):
    name: str
    value: int

and running the command poetry run mypy test.py, I get the following output with the current build:
test.py:1: error: Skipping analyzing "beanie": module is installed, but missing library stubs or py.typed marker

running the same command on this built version, I get the following output:
Success: no issues found in 1 source file

So mypy can find the py.typed file just fine now.

I have added a few types where I could, the big section I left as I don't really understand how the field gets converted to a string name is the /odm/operators/*.py field parameters. This should probably be looked at by someone with a bit more knowledge of the depths than me and can be looked at as a different task.

[nzsmith1]

Looks like I did not setup my environment correctly on my home PC, I will have a look at this mypy error tomorrow...

[wonjoonSeol-WS]

@nzsmith1
Hello, how did you deal with mypy errors after adding py.typed? I am still unable to update past 1.9.1 due to this issue.
#205