avoid rebuilding debug adapter on every codespace attach

Author: friendlymatthew

.devcontainer/devcontainer.json

@@ -5,7 +5,7 @@
         "ghcr.io/devcontainers/features/node:1": {}
     },
     "postCreateCommand": ".devcontainer/setup.sh",
-    "postAttachCommand": ".devcontainer/setup.sh && code --install-extension gabagool-debug-adapter/gabagool-debug.vsix --force",
+    "postAttachCommand": "code --install-extension gabagool-debug-adapter/gabagool-debug.vsix --force",
     "customizations": {
         "vscode": {
             "settings": {