added failling ubuntu test

Author: staabm

.github/workflows/e2e-tests.yml

@@ -382,6 +382,10 @@ jobs:
               composer install
               ../../bin/phpstan analyze test.php --level=0
             os: "ubuntu-latest"
+          - script: |
+              cd e2e/bug-12972
+              ../bashunit -a exit_code "1" ../../bin/phpstan
+            os: "ubuntu-latest"
           - script: |
               cd e2e/bug-12972
               ../../bin/phpstan analyze