GHA: Batch URIs to invalidate on Akamai

.github/actions/akamai-purge-osx/action.yml

@@ -31,6 +31,7 @@ runs:
           for idx in $indices
           do
             end=${idx%:*}
+            echo "Index ${end}"
             new_length=$((end-start))
             if [ $new_length -ge $MAX ]; then
               echo "Batch from ${offset} of length ${length}"