Bump celery from 4.3.0 to 4.4.0

Bumps [celery](https://github.com/celery/celery) from 4.3.0 to 4.4.0.
- [Release notes](https://github.com/celery/celery/releases)
- [Changelog](https://github.com/celery/celery/blob/master/Changelog.rst)
- [Commits](https://github.com/celery/celery/compare/v4.3.0...4.4.0)

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

setup.py

@@ -39,7 +39,7 @@ setup(
         'Flask-WTF==0.14.2',
         'Flask-Caching==1.8.0',
         'geopy==1.20.0',
-        'celery==4.3.0',
+        'celery==4.4.0',
         'redis==3.3.11',
         'aerofiles==1.0.0',
         'geoalchemy2==0.6.3',