Bump kombu from 4.3.0 to 4.4.0 in /requirements
Bump kombu from 4.3.0 to 4.4.0 in /requirements

Bumps [kombu](https://github.com/celery/kombu) from 4.3.0 to 4.4.0.
- [Release notes](https://github.com/celery/kombu/releases)
- [Changelog](https://github.com/celery/kombu/blob/master/Changelog)
- [Commits](https://github.com/celery/kombu/compare/v4.3.0...v4.4.0)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
KWierso/treeherder,edmorley/treeherder,KWierso/treeherder,edmorley/treeherder,KWierso/treeherder,KWierso/treeherder,edmorley/treeherder,edmorley/treeherder