Move minium ruby version to 3.3

[tomhughes]

Ruby 3.3 went EOL on 1st April which has prompted a number of gems to bump their minimum required version to 3.3 and that's only going to continue getting worse.

I don't think we can realistically continue to support it so this drops 3.2 support, unlocking a number of blocked gem updates in the process.

It also adds ruby 4.0 to the test matrix.

[tomhughes]

All updated, but MANUAL_INSTALL.md is still an issue as it uses Ubuntu 24.04 as it's primary target and that only has 3.2 available.

[pablobm]

@tomhughes - Do I understand correctly that you will update MANUAL_INSTALL.md as part of this PR? Or is that left for a separate one?

[tomhughes]

Well I can update it... I'm just not sure what to update it to say!

[hlfan]

Does Ubuntu 24.04 really not have Ruby 3.3 available? It's even listed in a rails guide...

https://guides.rubyonrails.org/install_ruby_on_rails.html

[tomhughes]

Yes where the instructions are to run some random shell script as root and then download a third party ruby from whatever source it provides after it's knackered your system.

It's not in the distro repo was my point.

[pablobm]

Right, so the issue is that Ubuntu 26.04 LTS is not out yet, is it? If I'm reading correctly, it's expected for this week and should include Ruby 3.3, so I guess we wait for this and update the manual install docs then?

[hlfan]

Or maybe just include a disclaimer on that combination and update the docs later. 26.04 LTS may impact more things.

[tomhughes]

Ubuntu 26.04 is out now so I've updated the manual install documentation to suggest that.

Oddly it only has 3.3 which might be a pain next year when that goes EOL and we need to think about 3.4 as a new baseline.

[hlfan]

I think this looks good now. Thank you!