Update test_can_be_used_as_personal_email to only skip if using GitHub Actions.

.github/workflows/main.yml

@@ -66,6 +66,8 @@ jobs:
       - name: Test with pytest
         run: |
           pytest
+        env:
+          GITHUB_ACTIONS_TEST: true
 
       - name: Archive code coverage results
         uses: actions/upload-artifact@v2

tests/test_email_utils.py

@@ -64,8 +64,9 @@ def test_email_belongs_to_alias_domains():
     assert not can_create_directory_for_address("hey@d3.test")
 
 
-@pytest.mark.skip(
-    reason="this test requires DNS lookup that does not work on Github CI"
+@pytest.mark.skipif(
+    "GITHUB_ACTIONS_TEST" in os.environ,
+    reason="this test requires DNS lookup that does not work on Github CI",
 )
 def test_can_be_used_as_personal_email(flask_client):
     # default alias domain