Upgrade maven-gpg-plugin 3.2.3 -> 3.2.4 (#1145)

See:
- https://github.com/apache/maven-gpg-plugin/releases/tag/maven-gpg-plugin-3.2.4
- apache/maven-gpg-plugin@maven-gpg-plugin-3.2.3...maven-gpg-plugin-3.2.4

pom.xml

@@ -1068,7 +1068,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-gpg-plugin</artifactId>
-                    <version>3.2.3</version>
+                    <version>3.2.4</version>
                     <executions>
                         <execution>
                             <id>sign-artifacts</id>