Ensure the CI complete step fails when tests fail

.github/workflows/haskell.yml

@@ -249,8 +249,18 @@ jobs:
     name: Tests completed
     runs-on: ubuntu-latest
     needs: test
+    if: always()
     steps:
-    - run: echo 'All tests completed successfully'
+    - run: |
+        case ${{ needs.test.result }} in
+          failure)
+            echo 'Some tests failed'
+            false;;
+          success)
+            echo 'All tests completed successfully';;
+          *)
+            echo 'Tests were ${{ needs.test.result }}';;
+        esac
 
   fourmolu:
     runs-on: ubuntu-latest