[ci] Try to make playground e2e tests less flaky

Not sure when this happened but the playground tests have gotten a little bit flaky. I suspect it's because of timeouts since it happens randomly so let's see if this helps.

Author: poteto

compiler/apps/playground/package.json

@@ -12,7 +12,7 @@
     "vercel-build": "yarn build",
     "start": "next start",
     "lint": "next lint",
-    "test": "playwright test"
+    "test": "playwright test --workers 6"
   },
   "dependencies": {
     "@babel/core": "^7.18.9",

compiler/apps/playground/playwright.config.js

@@ -17,7 +17,7 @@ const baseURL = `http://localhost:${PORT}`;
 // Reference: https://playwright.dev/docs/test-configuration
 export default defineConfig({
   // Timeout per test
-  timeout: 30 * 1000,
+  timeout: 60 * 1000,
   // Run all tests in parallel.
   fullyParallel: true,
   // Test directory