Add FakeDate to stubs

[srittau]

I'm using pysqlite3 instead of the built-in sqlite3 module, since I need newer features. Therefore I need to register FakeDate manually as an adapter for pysqlite3. Unfortunately, since FakeDate is not defined in freezegun/api.pyi, my type checkers complain about it. It would be useful to include FakeDate (and potentially other fake classes) in the type stubs.

[finswimmer]

Hey,

I second this. My use case is, that I write a custom representer for FakeDate in pyyaml.

Thanks a lot for this really cool project :+1:

[bblommers]

Freezegun 1.5.0 has proper (in-line) typing support, so I believe this is fixed.