Add support for Node 20, and drop support for Node 16

[Half-Shot]

As per https://github.com/nodejs/release#release-schedule, Node 20 has now been released and we will start testing for it. Node 16 is in maintenance and will no longer be supported. Node 18 is the last version we will support.

[justinbot]

One comment but looks good (looks like CI will be fixed by upgrading matrix-appservice after matrix-org/matrix-appservice-node#65)

[AndrewFerr]

Is now a good time to replace the npm commands in package.json (and docs files) with their yarn equivalents?

[AndrewFerr]

The dependencies of the two example modules (under ./examples) may as well be updated too. It turns out their lockfiles were quite out of whack, too. If it's welcomed, I prepared a commit to fix those issues that could be pushed here.

[Half-Shot]

The dependencies of the two example modules (under ./examples) may as well be updated too. It turns out their lockfiles were quite out of whack, too. If it's welcomed, I prepared a commit to fix those issues that could be pushed here.

Feel free, though longer term we need to sort out those examples. I think we always forget about them and CI don't care :p.

[AndrewFerr]

With the glibc compat issues resolved, this is finally done 😃