build(deps): bump unhead from 2.0.19 to 2.1.2

Bumps [unhead](https://github.com/unjs/unhead/tree/HEAD/packages/unhead) from 2.0.19 to 2.1.2.
- [Release notes](https://github.com/unjs/unhead/releases)
- [Commits](https://github.com/unjs/unhead/commits/v2.1.2/packages/unhead)

---
updated-dependencies:
- dependency-name: unhead
  dependency-version: 2.1.2
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]