Update sync-main-to-dev.yaml

Author: ralfhandl

.github/workflows/sync-main-to-dev.yaml

@@ -38,7 +38,7 @@ jobs:
           git fetch origin -v
           git checkout -b $SYNC origin/$SYNC || git checkout -b $SYNC origin/$BASE
 
-          git merge origin/$HEAD -m "Merge $HEAD into $SYNC"
+          git merge origin/$HEAD -m "Merge $HEAD into $SYNC" --allow-unrelated-histories
           git checkout origin/dev src/*
           git checkout origin/dev tests/*
           git commit -m "Restored src/* and tests/*"