fix(deps): update dependency @google-cloud/promisify to ^0.4.0 (#153)

Author: renovate[bot]

core/packages/nodejs-proto-files/package.json

@@ -39,7 +39,7 @@
     "predocs-test": "npm run docs"
   },
   "dependencies": {
-    "@google-cloud/promisify": "^0.3.1",
+    "@google-cloud/promisify": "^0.4.0",
     "protobufjs": "^6.8.0",
     "walkdir": "^0.3.0"
   },