Add debugging output to main workflow

.github/workflows/main_matrix.yml

@@ -306,6 +306,9 @@ jobs:
           name: firmware-${{ steps.version.outputs.version }}
           path: ./output
 
+      - name: Display structure of downloaded files
+        run: ls -R
+
       - name: Device scripts permissions
         run: |
           chmod +x ./output/device-install.sh