use latest node 20 release, start testing in node 22

[sqs]

Node 20.4.0 was old. It was behind what VS Code uses in Electron, and it was different from what the Kotlin bindings repo uses, which caused that step to fail locally.

Also, Node 20 enters maintenance (not active) phase soon: https://nodejs.org/en/about/previous-releases. Node 22 is the current release, so let's start running some CI jobs using it.

We could probably move to Node 22 now, but there is no reason to, and there's a slight benefit to having our main Node version match what VS Code uses (via Electron).

Test plan

CI