Bug 1791462 [wpt PR 35954] - Bump taskcluster from 44.18.0 to 44.21.0 in /tools, a=testonly

Automatic update from web-platform-tests
Bump taskcluster from 44.18.0 to 44.21.0 in /tools

Bumps [taskcluster](https://github.com/taskcluster/taskcluster) from 44.18.0 to 44.21.0.
- [Release notes](https://github.com/taskcluster/taskcluster/releases)
- [Changelog](https://github.com/taskcluster/taskcluster/blob/main/CHANGELOG.md)
- [Commits](https://github.com/taskcluster/taskcluster/compare/v44.18.0...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>
--

wpt-commits: f96321cbef3294ee6244cbe1aa6d194c3b7103cc
wpt-pr: 35954

testing/web-platform/tests/tools/ci/requirements_tc.txt

 pygithub==1.55
 pyyaml==6.0
 requests==2.27.1
-taskcluster==44.18.0
+taskcluster==44.21.0

testing/web-platform/tests/tools/requirements_tests.txt

@@ -2,4 +2,4 @@ httpx[http2]==0.22.0
 json-e==4.4.3
 jsonschema==3.2.0
 pyyaml==6.0
-taskcluster==44.18.0
+taskcluster==44.21.0