Bump celery from 4.2.1 to 5.2.2

Bumps [celery](https://github.com/celery/celery) from 4.2.1 to 5.2.2.
- [Release notes](https://github.com/celery/celery/releases)
- [Changelog](https://github.com/celery/celery/blob/master/Changelog.rst)
- [Commits](celery/celery@v4.2.1...v5.2.2)

---
updated-dependencies:
- dependency-name: celery
  dependency-type: direct:production
...

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

requirements.txt

@@ -6,7 +6,7 @@ timeago==1.0.10
 flower==0.9.5
 tornado<6
 sentry-sdk==1.14.0
-celery==4.2.1
+celery==5.2.2
 gevent==1.2.2
 greenlet==0.4.12
 whitenoise==4.1.2