fix: pnpm が command not found になるのを修正

.devcontainer/devcontainer.json

@@ -3,6 +3,9 @@
 	"dockerComposeFile": "docker-compose.yml",
 	"service": "app",
 	"workspaceFolder": "/workspace",
+	"features": {
+		"ghcr.io/devcontainers-contrib/features/pnpm:2": {}
+	},
 	"forwardPorts": [3000],
 	"postCreateCommand": "sudo chmod 755 .devcontainer/init.sh && .devcontainer/init.sh",
 	"customizations": {