build(deps): update dependency org.apache.maven.plugins:maven-gpg-plugin to v3.2.8

Author: renovate-bot

google-cloud-bom/pom.xml

@@ -368,7 +368,7 @@
           <plugin>
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-gpg-plugin</artifactId>
-            <version>3.2.7</version>
+            <version>3.2.8</version>
             <executions>
               <execution>
                 <id>sign-artifacts</id>

libraries-bom/pom.xml

@@ -149,7 +149,7 @@
           <plugin>
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-gpg-plugin</artifactId>
-            <version>3.2.7</version>
+            <version>3.2.8</version>
             <executions>
               <execution>
                 <id>sign-artifacts</id>