Bug 1770525 [wpt PR 34154] - Bump psutil from 5.9.0 to 5.9.1 in /tools, a=testonly

Automatic update from web-platform-tests
Bump psutil from 5.9.0 to 5.9.1 in /tools

Bumps [psutil](https://github.com/giampaolo/psutil) from 5.9.0 to 5.9.1.
- [Release notes](https://github.com/giampaolo/psutil/releases)
- [Changelog](https://github.com/giampaolo/psutil/blob/master/HISTORY.rst)
- [Commits](https://github.com/giampaolo/psutil/compare/release-5.9.0...release-5.9.1

)

---
updated-dependencies:
- dependency-name: psutil
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
--

wpt-commits: c63521d80d756c7a18cbd3070de3b96b2cd6e5cf
wpt-pr: 34154