Bump nexus-staging-maven-plugin from 1.6.3 to 1.6.8

Bumps nexus-staging-maven-plugin from 1.6.3 to 1.6.8.

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

pom.xml

@@ -130,7 +130,7 @@
          <plugin>
             <groupId>org.sonatype.plugins</groupId>
             <artifactId>nexus-staging-maven-plugin</artifactId>
-            <version>1.6.3</version>
+            <version>1.6.8</version>
             <extensions>true</extensions>
             <configuration>
                <autoReleaseAfterClose>true</autoReleaseAfterClose>