Bump celery from 5.0.5 to 5.2.2 in /metagov

Bumps [celery](https://github.com/celery/celery) from 5.0.5 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@v5.0.5...v5.2.2)

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

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

metagov/requirements.txt

@@ -9,7 +9,7 @@ backcall==0.2.0
 base58==2.1.0
 billiard==3.6.4.0
 black==20.8b1
-celery==5.0.5
+celery==5.2.2
 certifi==2020.12.5
 cffi==1.15.0
 chardet==4.0.0