ci: configure git in separate step; specify current branch when pushing new builscript version

.github/scripts/update-version.sh

@@ -1,13 +1,9 @@
 if [ ! -z $(git diff --name-only HEAD HEAD~1 | grep build.gradle) ]; then
   new_version="$(git log -n1 --format=format:"%H")"
   sed --in-place "s!//version:.*!//version: $new_version!g" build.gradle
-  
-  git config user.email "johann.bernhardt@tum.de"
-  git config user.name "Github CI Worker"
-  
   git add build.gradle
   git commit -m "[ci skip] update build script version to $new_version"
-  git push
+  git push origin ${GITHUB_REF##*/}
   echo "Updated buildscript version to $new_version"; 
 else
   echo "Ignored buildscript version update: no changes detected"