Bump celery from 5.2.3 to 5.2.6

Bumps [celery](https://github.com/celery/celery) from 5.2.3 to 5.2.6.
- [Release notes](https://github.com/celery/celery/releases)
- [Changelog](https://github.com/celery/celery/blob/v5.2.6/Changelog.rst)
- [Commits](celery/celery@v5.2.3...v5.2.6)

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

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

Author: dependabot[bot]

requirements/base.txt

@@ -3,7 +3,7 @@ django-environ==0.8.1
 psycopg2==2.9.3
 djangorestframework==3.13.1
 
-celery==5.2.3
+celery==5.2.6
 django-celery-results==2.3.0
 django-celery-beat==2.2.1