Bump html5ever from 0.38.0 to 0.39.0

Bumps [html5ever](https://github.com/servo/html5ever) from 0.38.0 to 0.39.0.
- [Release notes](https://github.com/servo/html5ever/releases)
- [Commits](https://github.com/servo/html5ever/commits)

---
updated-dependencies:
- dependency-name: html5ever
  dependency-version: 0.39.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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