Bump maven.version from 3.6.3 to 3.8.1 (#147)

Bumps `maven.version` from 3.6.3 to 3.8.1.

Updates `maven-plugin-api` from 3.6.3 to 3.8.1
- [Release notes](https://github.com/apache/maven/releases)
- [Commits](apache/maven@maven-3.6.3...maven-3.8.1)

Updates `maven-core` from 3.6.3 to 3.8.1
- [Release notes](https://github.com/apache/maven/releases)
- [Commits](apache/maven@maven-3.6.3...maven-3.8.1)

Updates `maven-artifact` from 3.6.3 to 3.8.1
- [Release notes](https://github.com/apache/maven/releases)
- [Commits](apache/maven@maven-3.6.3...maven-3.8.1)

Updates `maven-compat` from 3.6.3 to 3.8.1
- [Release notes](https://github.com/apache/maven/releases)
- [Commits](apache/maven@maven-3.6.3...maven-3.8.1)

Updates `maven-settings` from 3.6.3 to 3.8.1
- [Release notes](https://github.com/apache/maven/releases)
- [Commits](apache/maven@maven-3.6.3...maven-3.8.1)

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Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

pom.xml

@@ -34,7 +34,7 @@
         <versions.maven.plugin.version>2.8.1</versions.maven.plugin.version>
         <jira.rest.java.client.version>5.2.2</jira.rest.java.client.version>
         <fugue.version>4.7.2</fugue.version>
-        <maven.version>3.6.3</maven.version>
+        <maven.version>3.8.1</maven.version>
         <jgitflow.maven.plugin.version>1.0-m5.1</jgitflow.maven.plugin.version>
         <nexus.staging.maven.plugin.version>1.6.8</nexus.staging.maven.plugin.version>
         <maven.clean.plugin.version>3.1.0</maven.clean.plugin.version>