build(deps): bump taskcluster from 44.17.2 to 44.21.0 in /tools

Bumps [taskcluster](https://github.com/taskcluster/taskcluster) from 44.17.2 to 44.21.0.
- [Release notes](https://github.com/taskcluster/taskcluster/releases)
- [Changelog](https://github.com/taskcluster/taskcluster/blob/main/CHANGELOG.md)
- [Commits](taskcluster/taskcluster@v44.17.2...v44.21.0)

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

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

Author: dependabot[bot]

tools/requirements.txt

@@ -4,4 +4,4 @@ logbook==1.5.3
 pytz==2022.2.1
 raven==6.10.0
 structlog==22.1.0
-taskcluster==44.17.2
+taskcluster==44.21.0