Bump com.github.siom79.japicmp:japicmp-maven-plugin from 0.20.0 to 0.21.1 (#407)

Bump com.github.siom79.japicmp:japicmp-maven-plugin

Bumps [com.github.siom79.japicmp:japicmp-maven-plugin](https://github.com/siom79/japicmp) from 0.20.0 to 0.21.1.
- [Release notes](https://github.com/siom79/japicmp/releases)
- [Changelog](https://github.com/siom79/japicmp/blob/master/release.py)
- [Commits](siom79/japicmp@japicmp-base-0.20.0...japicmp-base-0.21.1)

---
updated-dependencies:
- dependency-name: com.github.siom79.japicmp:japicmp-maven-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

pom.xml

@@ -438,7 +438,7 @@
       <plugin>
         <groupId>com.github.siom79.japicmp</groupId>
         <artifactId>japicmp-maven-plugin</artifactId>
-        <version>0.20.0</version>
+        <version>0.21.1</version>
         <configuration>
           <parameter>
             <ignoreMissingOldVersion>true</ignoreMissingOldVersion>