concurrency hinzugefuegt

.github/workflows/docker_bullseye_target_unified.yml

@@ -1,5 +1,11 @@
 name: Test Install Scripts Target Unified
 
+# let only one instance run the test so cache is not corrupted.
+# cancel already running instances as only the last run will be relevant
+concurrency:
+    group: ${{ github.ref }}
+    cancel-in-progress: true
+
 on:
 #   schedule:
 #     # run at 5 every sunday