switch from js-yaml to yaml

[pi0]

Context: Pointed out by @remcohaszing in x npm:yaml is much more spec-compliant than npm:js-yaml

The main reason for choosing js-yaml was that it is ~10x faster and it is important for recurring reads (especially for cases like markdown front matter) but if spec compliant is better I think switch would make sense.

[remcohaszing]

You can see some reasoning in https://github.com/orgs/remarkjs/discussions/1006#discussioncomment-2955255. Also js-yaml hasn’t been updated for a while. It appears to be abandoned.