deps: update dependency com.google.auth:google-auth-library-bom to v1…

….6.0 (#631)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [com.google.auth:google-auth-library-bom](https://togithub.com/googleapis/google-auth-library-java) | `1.5.3` -> `1.6.0` | [![age](https://badges.renovateapi.com/packages/maven/com.google.auth:google-auth-library-bom/1.6.0/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/maven/com.google.auth:google-auth-library-bom/1.6.0/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/maven/com.google.auth:google-auth-library-bom/1.6.0/compatibility-slim/1.5.3)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/maven/com.google.auth:google-auth-library-bom/1.6.0/confidence-slim/1.5.3)](https://docs.renovatebot.com/merge-confidence/) |

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first-party-dependencies/pom.xml

@@ -63,7 +63,7 @@
     <google.api-common.version>2.1.4</google.api-common.version>
     <google.common-protos.version>2.7.4</google.common-protos.version>
     <google.core.version>2.5.10</google.core.version>
-    <google.auth.version>1.5.3</google.auth.version>
+    <google.auth.version>1.6.0</google.auth.version>
     <google.http-client.version>1.41.4</google.http-client.version>
     <google.oauth-client.version>1.33.1</google.oauth-client.version>
     <google.api-client.version>1.33.2</google.api-client.version>