Bump com.amashchenko.maven.plugin:gitflow-maven-plugin

Bumps [com.amashchenko.maven.plugin:gitflow-maven-plugin](https://github.com/aleksandr-m/gitflow-maven-plugin) from 1.20.0 to 1.21.0.
- [Release notes](https://github.com/aleksandr-m/gitflow-maven-plugin/releases)
- [Changelog](https://github.com/aleksandr-m/gitflow-maven-plugin/blob/master/CHANGELOG.md)
- [Commits](aleksandr-m/gitflow-maven-plugin@v1.20.0...v1.21.0)

---
updated-dependencies:
- dependency-name: com.amashchenko.maven.plugin:gitflow-maven-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

pom.xml

@@ -395,7 +395,7 @@
           <!-- gitflow -->
           <groupId>com.amashchenko.maven.plugin</groupId>
           <artifactId>gitflow-maven-plugin</artifactId>
-          <version>1.20.0</version>
+          <version>1.21.0</version>
           <configuration>
             <gitFlowConfig>
               <productionBranch>master</productionBranch>