build(deps): update dependency org.apache.maven.plugins:maven-gpg-plugin to v3.1.0 (#5971)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [org.apache.maven.plugins:maven-gpg-plugin](https://maven.apache.org/plugins/) | `3.0.1` -> `3.1.0` | [![age](https://badges.renovateapi.com/packages/maven/org.apache.maven.plugins:maven-gpg-plugin/3.1.0/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/maven/org.apache.maven.plugins:maven-gpg-plugin/3.1.0/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/maven/org.apache.maven.plugins:maven-gpg-plugin/3.1.0/compatibility-slim/3.0.1)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/maven/org.apache.maven.plugins:maven-gpg-plugin/3.1.0/confidence-slim/3.0.1)](https://docs.renovatebot.com/merge-confidence/) |

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google-cloud-bom/pom.xml

@@ -343,7 +343,7 @@
           <plugin>
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-gpg-plugin</artifactId>
-            <version>3.0.1</version>
+            <version>3.1.0</version>
             <executions>
               <execution>
                 <id>sign-artifacts</id>

libraries-bom/pom.xml

@@ -109,7 +109,7 @@
           <plugin>
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-gpg-plugin</artifactId>
-            <version>3.0.1</version>
+            <version>3.1.0</version>
             <executions>
               <execution>
                 <id>sign-artifacts</id>