check towncrier message format in lint ci

.github/workflows/test_fast.yml

@@ -106,6 +106,7 @@ jobs:
             echo "the following towncrier files may be wrong:"
             ls changes.d | grep ^[a-z].*.md
             exit 1
+          fi
 
       # note: exclude python 3.10+ from mypy checks as these produce false
       # positives in installed libraries for python 3.7