Update dependency org.sonatype.plugins:nexus-staging-maven-plugin to v1.6.8 (#678)

Author: renovate-bot

google-http-client-bom/pom.xml

@@ -117,7 +117,7 @@
       <plugin>
         <groupId>org.sonatype.plugins</groupId>
         <artifactId>nexus-staging-maven-plugin</artifactId>
-        <version>1.6.6</version>
+        <version>1.6.8</version>
         <extensions>true</extensions>
         <configuration>
           <serverId>sonatype-nexus-staging</serverId>

pom.xml

@@ -252,7 +252,7 @@
         <plugin>
           <groupId>org.sonatype.plugins</groupId>
           <artifactId>nexus-staging-maven-plugin</artifactId>
-          <version>1.6.6</version>
+          <version>1.6.8</version>
           <extensions>true</extensions>
           <configuration>
             <serverId>ossrh</serverId>