chore(type): use cast instead of assert

Author: cbartz

src/charm_state.py

@@ -226,13 +226,10 @@ def auth(self) -> GitHubAuth:
         """Build the application GitHub auth configuration."""
         if self.token is not None:
             return GitHubTokenAuth(token=self.token)
-        assert self.app_client_id is not None
-        assert self.installation_id is not None
-        assert self.private_key is not None
         return GitHubAppAuth(
-            app_client_id=self.app_client_id,
-            installation_id=self.installation_id,
-            private_key=self.private_key,
+            app_client_id=cast(str, self.app_client_id),
+            installation_id=cast(int, self.installation_id),
+            private_key=cast(str, self.private_key),
         )