Ruff enable type annotations rule (#362)

This PR enables the ruff rule for return type annotations (ANN), and
adds the ty package for type checking.

media_manager/auth/config.py

@@ -20,7 +20,3 @@ class AuthConfig(BaseSettings):
     admin_emails: list[str] = []
     email_password_resets: bool = False
     openid_connect: OpenIdConfig = OpenIdConfig()
-
-    @property
-    def jwt_signing_key(self):
-        return self._jwt_signing_key