Require Jenkins 2.387.3 or newer

[MarkEWaite]

Require Jenkins 2.387.3 or newer

• Upgrade HtmlUnit from 2.x to 3.x
• Require Jenkins 2.387.3 or newer
• Add workflow-cps version dependency for HTMLUnit 3 upgrade

Includes pull requests:

• Upgrade HtmlUnit from 2.x to 3.x #119

Supersedes pull requests:

• Bump bom-2.361.x from 2025.v816d28f1e04f to 2102.v854b_fec19c92 #118
• Bump plugin from 4.61 to 4.65 #117

Testing done

Automated tests pass with Java 11 on Linux.

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests - that demonstrates feature works or fixes the issue

[MarkEWaite]

@dwnusbaum or @car-roll or @rsandell could you approve and merge this pull request so that we can continue the HTMLUnit 3 upgrade process for the Jenkins plugin bill of materials?

See jenkinsci/bom#2158 (comment) for the list of components that have been detected as needing an update for the next release of the plugin bill of materials. 4 of 6 that need updates have been updated and released. This one would make 5 of 6 updated

[MarkEWaite]

It would be nice if this pull request could be labeled developer so that it would use the same changelog entry as other plugins have used.

[MarkEWaite]

Thanks very much @dwnusbaum !