chore: use commit hash for action

Author: MendixMobile

.github/workflows/sync.yml

@@ -16,7 +16,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5
         with:
           fetch-depth: 0
           ref: ${{ env.DEFAULT_BRANCH }}