build(deps): bump maven-plugin-plugin from 3.7.1 to 3.8.1

Bumps [maven-plugin-plugin](https://github.com/apache/maven-plugin-tools) from 3.7.1 to 3.8.1.
- [Release notes](https://github.com/apache/maven-plugin-tools/releases)
- [Commits](apache/maven-plugin-tools@maven-plugin-tools-3.7.1...maven-plugin-tools-3.8.1)

---
updated-dependencies:
- dependency-name: org.apache.maven.plugins:maven-plugin-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

maven/pom.xml

@@ -29,7 +29,7 @@ Copyright (c) 2013 Jeremy Long. All Rights Reserved.
     <inceptionYear>2013</inceptionYear>
     <properties>
         <!-- upgrading has caused publishing errors -->
-        <version.maven-plugin-plugin>3.7.1</version.maven-plugin-plugin>
+        <version.maven-plugin-plugin>3.8.1</version.maven-plugin-plugin>
     </properties>
     <scm>
         <connection>scm:git:https://github.com/jeremylong/DependencyCheck.git</connection>