docker: fix building PL image (Lightning-AI#17353)

Author: Borda

.github/workflows/ci-dockers-pytorch.yml

@@ -49,6 +49,8 @@ jobs:
           - {python_version: "3.10", pytorch_version: "2.0", cuda_version: "11.7.1"}
     steps:
       - uses: actions/checkout@v3
+        with:
+          submodules: true
       - uses: docker/setup-buildx-action@v2
       - uses: docker/build-push-action@v4
         with: