Python dependency: Bump testtools from 2.8.7 to 2.9.0 in /web/regression

Bumps [testtools](https://github.com/testing-cabal/testtools) from 2.8.7 to 2.9.0.
- [Release notes](https://github.com/testing-cabal/testtools/releases)
- [Changelog](https://github.com/testing-cabal/testtools/blob/master/NEWS)
- [Commits](testing-cabal/testtools@2.8.7...2.9.0)

---
updated-dependencies:
- dependency-name: testtools
  dependency-version: 2.9.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

web/regression/requirements.txt

@@ -29,5 +29,5 @@ pycodestyle>=2.5.0
 python-mimeparse==2.0.0
 selenium==4.41.0
 testscenarios==0.5.0
-testtools==2.8.7
+testtools==2.9.0
 traceback2==1.4.0