chore: release 2.5.0 (#272)

🤖 I have created a release \*beep\* \*boop\*
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## [2.5.0](https://www.github.com/googleapis/nodejs-cloudbuild/compare/v2.4.0...v2.5.0) (2021-08-23)


### Features

* turns on self-signed JWT feature flag ([#271](https://www.github.com/googleapis/nodejs-cloudbuild/issues/271)) ([dcb970d](https://www.github.com/googleapis/nodejs-cloudbuild/commit/dcb970d8a6a7d87da553667cd25f8eb1052ba047))
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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": "^2.4.0"
+    "@google-cloud/cloudbuild": "^2.5.0"
   },
   "devDependencies": {
     "c8": "^7.0.0",