Link to latest Nightly is added to the Changeset PR

[thecodedrift]

When a new nightly is published, the Changeset PR should include a region for the latest nightly:

<!-- nightly -->
### Build Info
`npx @taskless/cli@<version>`

**Built from:** <sha>
**Built at:** yyyy-mm-dd hh:mm:ss
<!-- /nightly -->

Changeset PRs exist for orchestration, and the PRs don't actually affect what goes into CHANGELOG.md

This build info should come at the end of the Changeset Pull Request. It can be removed safely, then re-attached at the end.

This workflow action must block on the npm publish. If there's no successful publish, there's nothing to update.