Update git-changelist-maven-extension if needed

[basil]

In addition to updating the plugin parent POM to the latest version, the version of git-changelist-maven-extension in .mvn/extensions.xml should be updated to the latest version if necessary. Version 1.6 is the last version that works on Java 8; 1.7 and later require Java 11+.

[timtebeek]

It looks like the closest we have to this might be the Add Gradle Enterprise Maven extension recipe at https://github.com/openrewrite/rewrite/blob/main/rewrite-maven/src/main/java/org/openrewrite/maven/AddGradleEnterpriseMavenExtension.java

While that adds a plugin, that might not be needed here, making this implementation easier by comparison. It does show we're already able to parse and manipulate maven extensions, so there should not be any hurdles to clear for this one.