Bump org.apache.maven:maven-core from 3.2.5 to 3.8.1

Bumps [org.apache.maven:maven-core](https://github.com/apache/maven) from 3.2.5 to 3.8.1.
- [Release notes](https://github.com/apache/maven/releases)
- [Commits](apache/maven@maven-3.2.5...maven-3.8.1)

---
updated-dependencies:
- dependency-name: org.apache.maven:maven-core
  dependency-type: direct:production
...

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

pom.xml

@@ -79,7 +79,7 @@
   </distributionManagement>
 
   <properties>
-    <mavenVersion>3.2.5</mavenVersion>
+    <mavenVersion>3.8.1</mavenVersion>
     <javaVersion>8</javaVersion>
     <sisu.version>0.3.5</sisu.version>
     <currentVersion>${project.version}</currentVersion>