Bump ezyang/htmlpurifier from 4.18.0 to 4.19.0

Bumps [ezyang/htmlpurifier](https://github.com/ezyang/htmlpurifier) from 4.18.0 to 4.19.0.
- [Release notes](https://github.com/ezyang/htmlpurifier/releases)
- [Changelog](https://github.com/ezyang/htmlpurifier/blob/master/NEWS)
- [Commits](ezyang/htmlpurifier@v4.18.0...v4.19.0)

---
updated-dependencies:
- dependency-name: ezyang/htmlpurifier
  dependency-version: 4.19.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]