Fix lint errors

tests/test_app.py

@@ -1,10 +1,12 @@
 #!/usr/bin/env python3
 
-import pytest
+"""Tests for app/app.py"""
+
 
 from tests import client
 
 
 def test_index(client) -> None:
+    """Ensure that the index page is loaded correctly."""
     req = client.get('/')
     assert req.status_code == 200 and "ePage" in req.text