GH Actions: run linting against ubuntu-latest

[jrfnl]

No description provided.

[Potherca]

For the sake of future sanity, I'd rather pin this to ubuntu-20.04. Support for ubuntu-22.04 is still in beta but whenever it is moved to latest by GitHub, I'd rahter not see things accidentally break. Or we could move to 22.4 now and not have to worry about updating things for at least another four years 🤷

Either way, I'd rather not use latest

[jrfnl]

@Potherca We're using latest for the tests and to be fair, the ubuntu version shouldn't really matter much for the checks being done here. Happy enough to pin it to 20-04 though.

[Potherca]

No, you are right... latest is fine here. The linter is not run on the host but in a container on the host.

I got my wires crossed somehow... 🤦