Adopt subversion plugin

[Maciej Jaros]

Hi,
I would like to adopt a plugin:

• Link: https://github.com/jenkinsci/subversion-plugin
• Status: for adoption
• GitHub Username: https://github.com/Eccenux
• Jenkins Infrastructure ID: nux
• Repository Permission Updater PR: https://github.com/jenkins-infra/repository-permissions-updater/pull/4951

I want to change the default format for SVN which is set to a very old version now (version 1.4). This breaks basic operations like svn:external currently so it is quite important. Even version 1.8 is quite old now (2013):
https://subversion.apache.org/news.html#:~:text=Apache%20Subversion%201%2E8%2E0%20Released
https://subversion.apache.org/docs/release-notes/
That problem with svn externals was reported before. I think that was in JIRA. Technically an easy fix (already run a test build), but tests and maybe deps need to be adjusted.

I would look into setting `env.SVN_REVISION` for pipeline use of the plugin. Not sure why that doesn't work.

Then I can check current stuff (there is an interesting pull request for svn cleanup, but seems to be missing tests, so might need some work).

At the company I work for we are using SVN extensively as we have a VERY large repository, so not planning to move to anything else any time soon.

Best regards,
Maciej Nux Jaros