Main changes:
- [Add LICENSE (LGPL)](https://github.com/djangsters/redis-tasks/commit/f6bdfff82bac80bcb39b0e3a60213ebf64c99180)
- [Set pythonpath in command line client](https://github.com/djangsters/redis-tasks/commit/34420da89c2f435583b8aab4ad02edb19d216e33)
- Dependency upgrade
- Remove support for python 3.6
- Add support for python 3.9