Make sandbox tests run concurrently

Author: cramforce

package.json

@@ -25,7 +25,7 @@
     "typecheck": "tsc --noEmit",
     "test": "vitest --exclude 'src/tool.vercel.integration.test.ts'",
     "test:run": "vitest run --exclude 'src/tool.vercel.integration.test.ts'",
-    "test:vercel": "vitest run --sequence.concurrent=false src/tool.vercel.integration.test.ts",
+    "test:vercel": "vitest run src/tool.vercel.integration.test.ts --sequence.concurrent",
     "lint": "biome check .",
     "lint:fix": "biome check --write .",
     "format": "biome format --write .",