Bump org.codehaus.mojo:flatten-maven-plugin from 1.7.3 to 1.8.0

Bumps [org.codehaus.mojo:flatten-maven-plugin](https://github.com/mojohaus/flatten-maven-plugin) from 1.7.3 to 1.8.0.
- [Release notes](https://github.com/mojohaus/flatten-maven-plugin/releases)
- [Commits](mojohaus/flatten-maven-plugin@1.7.3...1.8.0)

---
updated-dependencies:
- dependency-name: org.codehaus.mojo:flatten-maven-plugin
  dependency-version: 1.8.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

pom.xml

@@ -90,7 +90,7 @@
         <maven-gpg-plugin.version>3.2.8</maven-gpg-plugin.version>
         <sign-maven-plugin.version>1.1.0</sign-maven-plugin.version>
         <nexus-staging-maven-plugin.version>1.7.0</nexus-staging-maven-plugin.version>
-        <flatten-maven-plugin.version>1.7.3</flatten-maven-plugin.version>
+        <flatten-maven-plugin.version>1.8.0</flatten-maven-plugin.version>
         <asciidoctor-maven-plugin.version>3.2.0</asciidoctor-maven-plugin.version>
         <docbkx-maven-plugin.version>2.0.17</docbkx-maven-plugin.version>
         <build-helper-maven-plugin.version>3.6.1</build-helper-maven-plugin.version>