Bumps the CLI to 0.4.38 to cut a release including #9393 (the `priority`
section in `langgraph.json`), the only CLI change merged since 0.4.37.
The section takes effect with `langgraph-api` 0.18.0 or later; older
servers ignore it, and configs without it build the same images as
before.
Merging doesn't publish by itself: after it merges, run the `release`
workflow with `working-directory: libs/cli`.