Handle plugin warnings

[Ekryd]

[WARNING] Plugin validation issues were detected in 3 plugin(s)
[WARNING]
[WARNING] * org.jacoco:jacoco-maven-plugin:0.8.10
[WARNING] Declared at location(s):
[WARNING] * com.github.ekryd.sortpom:sortpom-parent:3.3.1-SNAPSHOT (pom.xml) @ line 341
[WARNING] Used in module(s):
[WARNING] * com.github.ekryd.sortpom:sortpom-parent:3.3.1-SNAPSHOT (pom.xml)
[WARNING] * com.github.ekryd.sortpom:sortpom-sorter:3.3.1-SNAPSHOT (sorter/pom.xml)
[WARNING] * com.github.ekryd.sortpom:sortpom-maven-plugin:3.3.1-SNAPSHOT (maven-plugin/pom.xml)
[WARNING] Plugin issue(s):
[WARNING] * Plugin is a Maven 2.x plugin, which will be not supported in Maven 4.x
[WARNING] * Plugin mixes multiple Maven versions: [3.0, 2.0.2]
[WARNING] * Plugin should declare these Maven artifacts in provided scope: [org.apache.maven:maven-repository-metadata:3.0, org.apache.maven:maven-artifact:3.0]
[WARNING] * Plugin depends on plexus-container-default, which is EOL
[WARNING]
[WARNING] * com.spotify.fmt:fmt-maven-plugin:2.20
[WARNING] Declared at location(s):
[WARNING] * com.github.ekryd.sortpom:sortpom-parent:3.3.1-SNAPSHOT (pom.xml) @ line 254
[WARNING] Used in module(s):
[WARNING] * com.github.ekryd.sortpom:sortpom-parent:3.3.1-SNAPSHOT (pom.xml)
[WARNING] * com.github.ekryd.sortpom:sortpom-sorter:3.3.1-SNAPSHOT (sorter/pom.xml)
[WARNING] * com.github.ekryd.sortpom:sortpom-maven-plugin:3.3.1-SNAPSHOT (maven-plugin/pom.xml)
[WARNING] Plugin issue(s):
[WARNING] * Plugin should declare these Maven artifacts in provided scope: [org.apache.maven:maven-artifact:3.8.7, org.apache.maven:maven-plugin-api:3.8.7, org.apache.maven:maven-model:3.8.7]
[WARNING]
[WARNING] * org.sonatype.plugins:nexus-staging-maven-plugin:1.6.13
[WARNING] Plugin issue(s):
[WARNING] * Plugin depends on the deprecated Maven 2.x compatibility layer, which may not be supported in Maven 4.x
[WARNING]
[WARNING]
[WARNING] Fix reported issues by adjusting plugin configuration or by upgrading above listed plugins. If no upgrade available, please notify plugin maintainers about reported issues.

[Ekryd]

Jacoco issue is solved: jacoco/jacoco#1435
fmt-maven-plugin warning is false positive: it needs to include org.apache.maven:maven-plugin-api since it starts a sub process.
Need to live with the warnings for nexus-staging-maven-plugin. There is no nice replacements