Improve python typings for PyCharm

[romantolkachyov]

Removes warnings in some cases like

URLPattern({"pathname": url_pattern})

PyCharm can't infer TypedDict | str alias.

[romantolkachyov]

This is how its look:

[bangseongbeom]

Thanks for attaching the screenshot! It made it easy for me to confirm that the same issue can be reproduced on my machine as well.

I suspect that PyCharm's built-in type checker is inferring the type incorrectly. The same issue does not occur in VS Code (Pyright).

In general, it's hard to justify changing the code just to work around a type checker's incorrect inference. However, PyCharm is a widely used IDE and there isn't a great alternative at the moment, so I agree that your proposed approach in this PR is the right direction.

I'll take a bit more time to look into similar cases and any other possible alternatives, and then merge it. Thanks again for your contribution!

[bangseongbeom]

Related: PY-42126, PY-74438