Don't rise warning for unused vars in sample

Author: Jorenar

pre-push.sample

@@ -2,6 +2,7 @@
 
 zero="$(git hash-object --stdin </dev/null | tr '0-9a-f' '0')"
 
+# shellcheck disable=SC2034
 while read -r local_ref local_oid remote_ref remote_oid
 do
     if [ "$local_oid" = "$zero" ]; then