build: add docker-in-docker

.devcontainer/devcontainer.json

@@ -7,7 +7,8 @@
 
 	// Features to add to the dev container. More info: https://containers.dev/features.
 	"features": {
-		"ghcr.io/devcontainers/features/desktop-lite:1": {}
+		"ghcr.io/devcontainers/features/desktop-lite:1": {},
+		"ghcr.io/devcontainers/features/docker-in-docker:2": {}
 	},
 
 	// Use 'forwardPorts' to make a list of ports inside the container available locally.