PYTHON-4572 - Fix type errors caused by new PyOpenSSL type hints (mongodb#1743)

(cherry picked from commit 0f5349e)

Author: NoahStapp

pymongo/pyopenssl_context.py

@@ -291,7 +291,7 @@ def load_cert_chain(
         # Password callback MUST be set first or it will be ignored.
         if password:
 
-            def _pwcb(_max_length: int, _prompt_twice: bool, _user_data: bytes) -> bytes:
+            def _pwcb(_max_length: int, _prompt_twice: bool, _user_data: Optional[bytes]) -> bytes:
                 # XXX:We could check the password length against what OpenSSL
                 # tells us is the max, but we can't raise an exception, so...
                 # warn?
@@ -331,6 +331,7 @@ def _load_certifi(self) -> None:
     def _load_wincerts(self, store: str) -> None:
         """Attempt to load CA certs from Windows trust store."""
         cert_store = self._ctx.get_cert_store()
+        assert cert_store is not None
         oid = _stdlibssl.Purpose.SERVER_AUTH.oid
 
         for cert, encoding, trust in _stdlibssl.enum_certificates(store):  # type: ignore