chore: release 2.3.1 (#266)

🤖 I have created a release \*beep\* \*boop\*
---
### [2.3.1](https://www.github.com/googleapis/nodejs-cloudbuild/compare/v2.3.0...v2.3.1) (2021-08-12)


### Bug Fixes

* **build:** migrate to using main branch ([#265](https://www.github.com/googleapis/nodejs-cloudbuild/issues/265)) ([e89f829](https://www.github.com/googleapis/nodejs-cloudbuild/commit/e89f829f10c5710ca5fb259a6c8dfae1527071a3))
---


This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please).

cloudbuild/package.json

@@ -15,7 +15,7 @@
     "test": "c8 mocha system-test --timeout=800000"
   },
   "dependencies": {
-    "@google-cloud/cloudbuild": "^2.3.0"
+    "@google-cloud/cloudbuild": "^2.3.1"
   },
   "devDependencies": {
     "c8": "^7.0.0",