Bump versions-maven-plugin from 2.7 to 2.8.1 (#710)

Author: dependabot[bot]

pom.xml

@@ -75,7 +75,7 @@
         <plugin>
           <groupId>org.codehaus.mojo</groupId>
           <artifactId>versions-maven-plugin</artifactId>
-          <version>2.7</version>
+          <version>2.8.1</version>
         </plugin>
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>