Bump celery from 5.2.3 to 5.2.6 (#541)

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] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Mariatta Wijaya <[email protected]>

Author: dependabot[bot]

requirements.txt

@@ -4,6 +4,6 @@ aiohttp==3.8.1
 gidgethub==5.1.0
 cachetools==5.0.0
 redis==4.1.2
-celery==5.2.3
+celery==5.2.6
 sentry-sdk==1.5.9
 click==8.0.3