Bump plexus from 6.1 to 6.4

dependabot[bot] · web-flow · commit 1cc88f1fe849 · 2020-08-16T09:05:19.000Z
Bumps [plexus](https://github.com/codehaus-plexus/plexus-pom) from 6.1 to 6.4. - [Release notes](https://github.com/codehaus-plexus/plexus-pom/releases) - [Commits](codehaus-plexus/plexus-pom@plexus-6.1...plexus-6.4) Signed-off-by: dependabot[bot] <support@github.com>
diff --git a/pom.xml b/pom.xml
@@ -22,7 +22,7 @@ limitations under the License.
   <parent>
     <groupId>org.codehaus.plexus</groupId>
     <artifactId>plexus</artifactId>
-    <version>6.1</version>
+    <version>6.4</version>
   </parent>
 
   <artifactId>plexus-utils</artifactId>
