Bump nexus-staging-maven-plugin from 1.6.7 to 1.6.8 (#52)

Author: dependabot[bot]

pom.xml

@@ -320,7 +320,7 @@
             <plugin>
                 <groupId>org.sonatype.plugins</groupId>
                 <artifactId>nexus-staging-maven-plugin</artifactId>
-                <version>1.6.7</version>
+                <version>1.6.8</version>
                 <extensions>true</extensions>
                 <configuration>
                     <serverId>ossrh</serverId>