Bump billiard from 4.2.0 to 4.2.1

Bumps [billiard](https://github.com/celery/billiard) from 4.2.0 to 4.2.1.
- [Release notes](https://github.com/celery/billiard/releases)
- [Changelog](https://github.com/celery/billiard/blob/main/CHANGES.txt)
- [Commits](celery/billiard@v4.2.0...v4.2.1)

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

Signed-off-by: dependabot[bot] <[email protected]>

requirements.txt

@@ -8,7 +8,7 @@ async-timeout==4.0.3
 attrs==24.2.0
 Authlib==1.3.2
 beautifulsoup4==4.12.3
-billiard==4.2.0
+billiard==4.2.1
 black==24.8.0
 boto3==1.34.158
 botocore==1.34.158