Bump plexusCompilerVersion from 2.8.8 to 2.9.0

Bumps `plexusCompilerVersion` from 2.8.8 to 2.9.0.

Updates `plexus-compiler-api` from 2.8.8 to 2.9.0
- [Release notes](https://github.com/codehaus-plexus/plexus-compiler/releases)
- [Commits](codehaus-plexus/plexus-compiler@plexus-compiler-2.8.8...plexus-compiler-2.9.0)

Updates `plexus-compiler-manager` from 2.8.8 to 2.9.0
- [Release notes](https://github.com/codehaus-plexus/plexus-compiler/releases)
- [Commits](codehaus-plexus/plexus-compiler@plexus-compiler-2.8.8...plexus-compiler-2.9.0)

Updates `plexus-compiler-javac` from 2.8.8 to 2.9.0

---
updated-dependencies:
- dependency-name: org.codehaus.plexus:plexus-compiler-api
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: org.codehaus.plexus:plexus-compiler-manager
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: org.codehaus.plexus:plexus-compiler-javac
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

pom.xml

@@ -68,7 +68,7 @@ under the License.
  ! The following property is used in the integration tests MCOMPILER-157
  -->
  <mavenPluginPluginVersion>3.5</mavenPluginPluginVersion>
- <plexusCompilerVersion>2.8.8</plexusCompilerVersion>
+ <plexusCompilerVersion>2.9.0</plexusCompilerVersion>
  <groovyVersion>2.4.21</groovyVersion>
  <groovyEclipseCompilerVersion>3.7.0</groovyEclipseCompilerVersion>
  <groovy-eclipse-batch>2.5.14-02</groovy-eclipse-batch>