Update nbgv_dotnet_pack.yml

Author: varndellwagglebee

.github/workflows/nbgv_dotnet_pack.yml

@@ -35,7 +35,9 @@ jobs:
     steps:
       - name: ⬇️  Checkout
         uses: actions/checkout@v4
-        with: { fetch-depth: 0 }
+        with:
+          ref: ${{ inputs.checkout_ref }}   # caller-supplied branch/tag/SHA
+          fetch-depth: 0
 
       - name: 🛠️  Setup .NET
         uses: actions/setup-dotnet@v4