build(deps): bump testfixtures from 7.1.0 to 7.2.2

Bumps [testfixtures](https://github.com/Simplistix/testfixtures) from 7.1.0 to 7.2.2.
- [Changelog](https://github.com/simplistix/testfixtures/blob/master/CHANGELOG.rst)
- [Commits](simplistix/testfixtures@7.1.0...7.2.2)

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

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