Update dependency org.apache.maven.plugins:maven-gpg-plugin to v3.2.8

Author: renovate[bot]

pom.xml

@@ -256,7 +256,7 @@
                     <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>