build: revert incompatible upgrade

Author: subfuzion

scheduler/package.json

@@ -20,7 +20,7 @@
     "@google-cloud/scheduler": "^4.0.0"
   },
   "devDependencies": {
-    "@types/chai": "^5.0.0",
+    "@types/chai": "^4.5.0",
     "@types/mocha": "^10.0.1",
     "@types/node": "^22.0.0",
     "c8": "^10.0.0",