Add ubuntu 22.04 to the build pipeline

[timo-a]

This PR adds a build on ubuntu 22.04 to the github workflows.
This PR is also evidence that #1474 is solved (I haven't tried to build locally though, only fiddled with the yml files).

[duanqn]

Do you have a successful run for the new workflow somewhere?

[TheJJ]

thanks!
now that 22.04 works, i think we can remove 21.04, it won't be supported much longer anyway

[duanqn]

thanks! now that 22.04 works, i think we can remove 21.04, it won't be supported much longer anyway

Agreed. :)

[timo-a]

Do you have a successful run for the new workflow somewhere?

Yes, over at my fork: https://github.com/timo-a/openage/actions/runs/2405696342

[timo-a]

thanks! now that 22.04 works, i think we can remove 21.04, it won't be supported much longer anyway

Agreed. :)

I have removed 21.04 from the branch of the PR.
(most recent successful run is now https://github.com/timo-a/openage/actions/runs/2411215395)

[heinezen]

@timo-a Great!

Can you also remove the references to old Ubuntu in the build instructions with your PR. Because we don't need those anymore :)

[duanqn]

@timo-a Great!

Can you also remove the references to old Ubuntu in the build instructions with your PR. Because we don't need those anymore :)

You mean the Ubuntu 20.04 instructions?

[heinezen]

I've squashed your changes for the Workflow creation. Looks good.

[heinezen]

Good job!