ci: use git LFS for penumbra docker build

According to [0] if we pass in a custom context with git
lfs enabled then the build should work.

[0] docker/build-push-action#312

.github/workflows/containers.yml

@@ -19,6 +19,8 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
+        with:
+          lfs: true
 
       - name: Set up QEMU
         uses: docker/setup-qemu-action@v2