Change scope of Maven Plugin API Dependency

[marschall]

Change the scope of the maven-plugin-api to provided.

When building with Maven 3.9.2 with -Dmaven.plugin.validation=VERBOSE I get the following warning:

WARNING] Plugin validation issues were detected in 5 plugin(s)
[WARNING] 
[WARNING]  * org.apache.maven.plugins:maven-jar-plugin:3.0.2
...
[WARNING]    * Plugin should declare these Maven artifacts in `provided` scope: [org.apache.maven:maven-settings-builder:3.0, org.apache.maven:maven-repository-metadata:3.0, org.apache.maven:maven-artifact:3.0, org.apache.maven:maven-plugin-api:3.0, org.apache.maven:maven-settings:3.0, org.apache.maven:maven-aether-provider:3.0, org.apache.maven:maven-model:3.0, org.apache.maven:maven-core:3.0, org.apache.maven:maven-model-builder:3.0]