[build] Update Nexus staging plugin to 1.6.13

Author: fpapon

pom.xml

@@ -123,7 +123,7 @@
       <plugin>
         <groupId>org.sonatype.plugins</groupId>
         <artifactId>nexus-staging-maven-plugin</artifactId>
-        <version>1.6.8</version>
+        <version>1.6.13</version>
         <extensions>true</extensions>
         <configuration>
           <serverId>ossrh</serverId>