test: ensure returned user object is not None [scidsg#447]

Suggested in review:
scidsg#447 (comment)

Co-authored-by: Jeremy Moore <jeremymoore@gmail.com>

tests/test_settings.py

@@ -107,8 +107,8 @@ def test_change_password(client: FlaskClient) -> None:
 
     # Log in the registered user
     logged_in_user = login_user(client, username, original_password)
-    if logged_in_user is not None:
-        assert user.id == logged_in_user.id
+    assert logged_in_user is not None
+    assert user.id == logged_in_user.id
 
     # Submit POST request to change the username & verify update was successful
     response = client.post(