fix bug in github workflow for commit bot

Author: ctnguyen

.github/workflows/build_bdk.yaml

@@ -20,7 +20,7 @@ jobs:
       - name: Check out repository
         uses: actions/checkout@v4
         with:
-          ref: ${{ github.event.pull_request.head.sha }}
+          ref: ${{ github.head_ref }}
           fetch-depth: 0
 
       - name: Set up Python 3
@@ -122,6 +122,9 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4
+        with:
+          ref: ${{ github.head_ref }}
+          fetch-depth: 0
 
       - name: Download all gobdk static libraries artifacts
         uses: actions/download-artifact@v4