[no ticket] only bother slack on failure (#2832)

## Context

This was always the intention here, I just forgot to adjust the
condition

.github/workflows/vulnerability-scans.yml

@@ -247,7 +247,7 @@ jobs:
           accept-filenames: ${{ env.DOCKLE_ACCEPT_FILES }}
 
       - name: Save output to workflow summary
-        if: always() # Runs even if there is a failure
+        if: failure() # Only runs if there is a failure
         run: |
           {
             echo '```json'