test: Adapt test to updated com.github.mwiede:jsch

[gschafra]

• See Old version of jsch is incompatible with new versions of OpenSSH servers #292, as explained in https://stackoverflow.com/questions/72743823/public-key-authentication-fails-with-jsch-but-work-with-openssh-with-the-same-ke
• Minimum Java version required is now 11
• Package updates (minor)
• Needed for https://github.com/jenkinsci/ssh-steps-plugin, should fix https://issues.jenkins.io/browse/JENKINS-65533?jql=resolution%20is%20EMPTY%20and%20component%3D23921
• Dropped support for ssh-rsa type keys, see https://github.com/mwiede/jsch#why-do-ssh-rsa-type-keys-not-work-with-this-jsch-fork-and-my-server
• Dropped jcenter() repo in favour of mavenCentral()

This fixes the bug #292

Steps to verify the fix

1. SSH connect to a SSH server running OpenSSH 7.8+ with a newer key (e.g. ed25519)

Backward compatibility

• Dropped Java v8 support, minimum Java version is now 11
• Dropped support for ssh-rsa type keys, see https://github.com/mwiede/jsch#why-do-ssh-rsa-type-keys-not-work-with-this-jsch-fork-and-my-server

[elijahfhopp]

Hey, sorry about #294 . I really didn't see this before I made my changes. I think they are different enough to warrant a different PR. I did copy your comment/code for the user agent auth code bit. It was much better then I had. Thanks!

[gschafra]

Hey @mrzeusthecoder! No Problem, quite the opposite, I'm really relieved that some one has taken care of this, even if it's in another PR, because I'm I simply lack deeper experience in Java/Groovy/Gradle/Maven. Because of this, I've seen this PR as a more or less good starting point for someone more experience to follow up on... as you did. So, thanks you. So do you think I can close my PR in favour of yours? Or are there still such significant differences which would justify to keep this PR?

[elijahfhopp]

@gschafra Ok, good to hear. Never know how people might take that. I would say keep it open if only for the CI changes you made. Depending on how my PR goes, I would totally be willing to get that back up and running. I don't exactly know the changes you made, but they seemed somewhat significant.

Honestly, just do what you'd like. It doesn't seem like this repo is active enough to have any super strict contribution guidelines, 😊 .