Clone submodules

Author: abetlen

.github/workflows/build-docker.yaml

@@ -9,6 +9,8 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v3
+        with:
+          submodules: "true"
 
       - name: Set up QEMU
         uses: docker/setup-qemu-action@v2