use timestamp to version buildscript

.github/scripts/update-version.sh

@@ -1,5 +1,5 @@
 if [ ! -z $(git diff --name-only HEAD HEAD~1 | grep build.gradle) ]; then
-  new_version="$(git log -n1 --format=format:"%H")"
+  new_version="$(date +%s)"
   sed --in-place "s!^//version:.*!//version: $new_version!g" build.gradle
   git add build.gradle
   git commit -m "[ci skip] update build script version to $new_version"