chore: release 3.21.0 (#576)

🤖 I have created a release \*beep\* \*boop\*
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## [3.21.0](https://www.github.com/googleapis/nodejs-asset/compare/v3.20.0...v3.21.0) (2021-11-09)


### Features

* OSConfig: add OS policy assignment rpcs ([#574](https://www.github.com/googleapis/nodejs-asset/issues/574)) ([ff9491d](https://www.github.com/googleapis/nodejs-asset/commit/ff9491d55bd527c451914b487ce08fed3068dbd8))
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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]

asset/snippets/package.json

@@ -15,7 +15,7 @@
     "test": "mocha --timeout 360000"
   },
   "dependencies": {
-    "@google-cloud/asset": "^3.20.0",
+    "@google-cloud/asset": "^3.21.0",
     "@google-cloud/bigquery": "^5.5.0",
     "@google-cloud/compute": "^2.0.0",
     "@google-cloud/storage": "^5.0.0",