Bump com.github.siom79.japicmp:japicmp-maven-plugin (#5077)

Bumps [com.github.siom79.japicmp:japicmp-maven-plugin](https://github.com/siom79/japicmp) from 0.15.6 to 0.20.0.
- [Release notes](https://github.com/siom79/japicmp/releases)
- [Changelog](https://github.com/siom79/japicmp/blob/master/release.py)
- [Commits](siom79/japicmp@japicmp-base-0.15.6...japicmp-base-0.20.0)

---
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] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

pom.xml

@@ -156,7 +156,7 @@
         <exec-maven-plugin.version>1.6.0</exec-maven-plugin.version>
         <maven-deploy-plugin.version>2.8.2</maven-deploy-plugin.version>
         <build-helper-maven-plugin.version>3.3.0</build-helper-maven-plugin.version>
-        <japicmp-maven-plugin.version>0.15.6</japicmp-maven-plugin.version>
+        <japicmp-maven-plugin.version>0.20.0</japicmp-maven-plugin.version>
         <versions-maven-plugin.version>2.13.0</versions-maven-plugin.version>
         <maven-archetype-plugin.version>3.2.1</maven-archetype-plugin.version>
         <!-- Whenever we update maven-wrapper-plugin version, we need to run mvn wrapper:wrapper to update the Maven Wrapper files(mvnw, .maven and mvnw.cmd) -->