Migrate patch-diff-report-tool to Version 21

[aclfe]

The patch-diff-report-tool in the contribution repo is configured for Java 17 (in its pom.xml)
https://github.com/checkstyle/contribution/blob/master/patch-diff-report-tool/pom.xml

but the Checkstyle master branch now requires Java 21.

I ran Github, generate report and it fails due to version mismatch. Logs attached here:

Error:  Failed to execute goal org.apache.maven.plugins:maven-enforcer-plugin:3.6.2:enforce (enforce-versions) on project checkstyle: 
Error:  Rule 0: org.apache.maven.enforcer.rules.version.RequireJavaVersion failed with message:
Error:  Detected JDK /usr/lib/jvm/temurin-17-jdk-amd64 is version 17.0.17 which is not in the allowed range [21,).
Error:  -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-enforcer-plugin:3.6.2:enforce (enforce-versions) on project checkstyle: 
Rule 0: org.apache.maven.enforcer.rules.version.RequireJavaVersion failed with message:
Detected JDK /usr/lib/jvm/temurin-17-jdk-amd64 is version 17.0.17 which is not in the allowed range [21,).
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:314)
Caused by: org.apache.maven.plugin.MojoExecutionException: 
Rule 0: org.apache.maven.enforcer.rules.version.RequireJavaVersion failed with message:
Detected JDK /usr/lib/jvm/temurin-17-jdk-amd64 is version 17.0.17 which is not in the allowed range [21,).

I believe this needs updating in order to make the github action work

[vivek-0509]

Noticed the same issue here:
https://github.com/checkstyle/checkstyle/actions/runs/20864792755/job/59953437411

[romani]

Yes, we need help with migration, if you see how to fix it, please send PR

[aclfe]

Yes, we need help with migration, if you see how to fix it, please send PR

Yup, on it

[aclfe]

Hello, I checked appveyor.yml and I saw the flow goes like this:

    # checkstyle and sevntu.checkstyle
    - JAVA_HOME: C:\Program Files\Java\JDK21
      DESC: "releasenotes-builder"
      CMD1: "cd releasenotes-builder && mvn clean verify && mvn clean compile package"
    # verify without checkstyle
    - JAVA_HOME: C:\Program Files\Java\JDK21
      DESC: "patch-diff-report-tool"
      CMD1: "cd patch-diff-report-tool && mvn clean install"

Naturally I checked releasenotes-builder and patch-diff-report-tool pom.xmls and they had version 17 in there. After changing it, I believe that might be the solution.

PR is here: #1018

Though my concern is the original error can't seem to be locally reproduced in my machine. Can someone check over with this?