chore: release 3.15.0 (#516)

🤖 I have created a release \*beep\* \*boop\*
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## [3.15.0](https://www.github.com/googleapis/nodejs-asset/compare/v3.14.1...v3.15.0) (2021-06-30)


### Features

* add new searchable fields (memberTypes, roles, project, folders and organization), new request fields (assetTypes and orderBy) and new response fields (assetType, folders and organization) in SearchAllIamPolicies ([#511](https://www.github.com/googleapis/nodejs-asset/issues/511)) ([1dfb0e9](https://www.github.com/googleapis/nodejs-asset/commit/1dfb0e95c58fdfbca2807744ea22c52d3c6e7651))
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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).

asset/snippets/package.json

@@ -15,7 +15,7 @@
     "test": "mocha --timeout 180000"
   },
   "dependencies": {
-    "@google-cloud/asset": "^3.14.1",
+    "@google-cloud/asset": "^3.15.0",
     "@google-cloud/bigquery": "^5.5.0",
     "@google-cloud/compute": "^2.0.0",
     "@google-cloud/storage": "^5.0.0",