chore(deps): update ghcr.io/devcontainers/features/docker-in-docker docker tag to v4 (#253)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| ghcr.io/devcontainers/features/docker-in-docker | feature | major |
`2` → `4` |

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Author: ecv

.devcontainer/devcontainer.json

@@ -2,7 +2,7 @@
   "name": "Kubebuilder DevContainer",
   "image": "docker.io/golang:1.26",
   "features": {
-    "ghcr.io/devcontainers/features/docker-in-docker:2": {},
+    "ghcr.io/devcontainers/features/docker-in-docker:4": {},
     "ghcr.io/devcontainers/features/git:1": {}
   },