Bump plexusCompilerVersion from 2.11.2-SNAPSHOT to 2.12.0

Bumps `plexusCompilerVersion` from 2.11.2-SNAPSHOT to 2.12.0.

Updates `plexus-compiler-api` from 2.11.2-SNAPSHOT to 2.12.0
- [Release notes](https://github.com/codehaus-plexus/plexus-compiler/releases)
- [Commits](https://github.com/codehaus-plexus/plexus-compiler/commits/plexus-compiler-2.12.0)

Updates `plexus-compiler-manager` from 2.11.2-SNAPSHOT to 2.12.0
- [Release notes](https://github.com/codehaus-plexus/plexus-compiler/releases)
- [Commits](https://github.com/codehaus-plexus/plexus-compiler/commits/plexus-compiler-2.12.0)

Updates `plexus-compiler-javac` from 2.11.2-SNAPSHOT to 2.12.0

---
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>2.11.2-SNAPSHOT</plexusCompilerVersion>
+    <plexusCompilerVersion>2.12.0</plexusCompilerVersion>
 
     <groovyVersion>2.4.21</groovyVersion>
     <groovyEclipseCompilerVersion>3.7.0</groovyEclipseCompilerVersion>