Fix: bump-version fetch+checkout main vor push

.gitlab-ci.yml

@@ -126,6 +126,9 @@ bump-version:
       git config user.name "GitLab CI"
       git config user.email "ci@adriahub.de"
       git remote set-url origin "http://oauth2:${CI_PUSH_TOKEN}@192.168.1.100:9080/${CI_PROJECT_PATH}.git"
+      git fetch origin main
+      git checkout main
+      echo "$NEXT_VERSION" > VERSION
       git add VERSION
       git commit -m "v${NEXT_VERSION} [skip ci]"
-      git push origin HEAD:main
+      git push origin main