chore: release 4.2.0 (#858)

🤖 I have created a release \*beep\* \*boop\*
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## [4.2.0](https://www.github.com/googleapis/nodejs-dialogflow/compare/v4.1.4...v4.2.0) (2021-08-10)


### Features

* Expose `Locations` service to get/list avaliable locations of Dialogflow products docs: reorder some fields ([#857](https://www.github.com/googleapis/nodejs-dialogflow/issues/857)) ([4ffc775](https://www.github.com/googleapis/nodejs-dialogflow/commit/4ffc775af328735a00ba075e75e1065c3b1dd308))
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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).

Author: release-please[bot]

dialogflow/package.json

@@ -15,7 +15,7 @@
     "test": "mocha system-test --timeout=600000"
   },
   "dependencies": {
-    "@google-cloud/dialogflow": "^4.1.4",
+    "@google-cloud/dialogflow": "^4.2.0",
     "pb-util": "^1.0.0",
     "uuid": "^8.0.0",
     "yargs": "^16.0.0"