CI: Add cancellation support to check-tags job

Author: markgoddard

.github/workflows/stackhpc-check-tags.yml

@@ -23,7 +23,7 @@ env:
 jobs:
   check-tags:
     name: Check container image tags
-    if: inputs.if
+    if: ${{ inputs.if && ! cancelled() }}
     runs-on: arc-skc-aio-runner
     permissions: {}
     env: