Bump com.github.siom79.japicmp:japicmp-maven-plugin (#2525)

Bumps [com.github.siom79.japicmp:japicmp-maven-plugin](https://github.com/siom79/japicmp) from 0.18.2 to 0.18.3.
- [Release notes](https://github.com/siom79/japicmp/releases)
- [Changelog](https://github.com/siom79/japicmp/blob/master/release.py)
- [Commits](https://github.com/siom79/japicmp/compare/japicmp-base-0.18.2...japicmp-base-0.18.3)

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

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Éamonn McManus <emcmanus@google.com>

pom.xml

@@ -299,7 +299,7 @@
         <plugin>
           <groupId>com.github.siom79.japicmp</groupId>
           <artifactId>japicmp-maven-plugin</artifactId>
-          <version>0.18.2</version>
+          <version>0.18.3</version>
           <configuration>
             <oldVersion>
               <dependency>