deps: update dependency com.google.errorprone:error_prone_annotations to v2.7.1 (googleapis#451)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| com.google.errorprone:error_prone_annotations | `2.6.0` -> `2.7.1` | [![age](https://badges.renovateapi.com/packages/maven/com.google.errorprone:error_prone_annotations/2.7.1/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/maven/com.google.errorprone:error_prone_annotations/2.7.1/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/maven/com.google.errorprone:error_prone_annotations/2.7.1/compatibility-slim/2.6.0)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/maven/com.google.errorprone:error_prone_annotations/2.7.1/confidence-slim/2.6.0)](https://docs.renovatebot.com/merge-confidence/) |

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pom.xml

@@ -169,7 +169,7 @@
     <findbugs.version>3.0.2</findbugs.version>
     <threetenbp.version>1.5.1</threetenbp.version>
     <objenesis.version>2.6</objenesis.version>
-    <errorprone.version>2.6.0</errorprone.version>
+    <errorprone.version>2.7.1</errorprone.version>
     <gson.version>2.8.6</gson.version>
   </properties>