fix(mcserver): change required jdk to 21

[MicLieg]

Description

As of the latest patch, minecraft now requires Java 21 to run:

The game now requires Java 21

Other distro's csv files also have to be updated.

Fixes #4564

Type of change

• Bug fix (a change which fixes an issue).
• New feature (a change which adds functionality).
• New Server (new server added).
• Refactor (restructures existing code).
• Comment update (typo, spelling, explanation, examples, etc).

Checklist

PR will not be merged until all steps are complete.

• This pull request links to an issue.
• This pull request uses the develop branch as its base.
• This pull request subject follows the Conventional Commits standard.
• This code follows the style guidelines of this project.
• I have performed a self-review of my code.
• I have checked that this code is commented where required.
• I have provided a detailed enough description of this PR.
• I have checked if documentation needs updating.

Documentation

If documentation does need updating either update it by creating a PR (preferred) or request a documentation update.

• User docs: https://github.com/GameServerManagers/LinuxGSM-Docs
• Dev docs: https://github.com/GameServerManagers/LinuxGSM-Dev-Docs

Thank you for your Pull Request!

[dgibbs64]

This PR will need the other distros added in as well rather than needing 2 seperate PR's

[MicLieg]

I agree.
Unfortunately I'm not sure how to efficiently identify which distribution provides openjdk-21-jre by default. I thnik given that most users are running Ubuntu, and that the next most popular distribution, Debian, doesn't seem to include Java 21 out of the box, it's worth fixing this issue for over 60% of LGSM users right now, before wating for a fix for all the other distros.

If there's an easy way of checking wether the other distros offer Java 21, i'll happily update this PR.

[dgibbs64]

I have sorted it as I have needed to do this before 😃