update image

.devcontainer/devcontainer.json

@@ -14,5 +14,5 @@
     3000,
     9944
   ],
-  "image": "paritytech/substrate-playground-template-node-template:sha-7a3d8d6"
+  "image": "paritytech/substrate-playground-template-node-template:sha-912fa0f"
 }