Pyrate-limiter

* Fix Redis CROSSSLOT Keys following issue [126](https://github.com/vutran1710/PyrateLimiter/issues/126)

* Fix broken SqliteBucket following issue [132](https://github.com/vutran1710/PyrateLimiter/issues/132)

* Allow to pass rates directly to Limiter to use default ImMemoryBucket with Limiter
* Allow to pass *Duration* to `max_delay` argument of Limiter

* Critical bug fix: importing redis fail crashing apps

Third major release with API breaking changes:
- Drop python 3.7 (only python ^3.8)
- Bucket must be initialized before passing to Limiter
- Auto leaking (provided by BucketFactory)
- Decorator API changes
- Limiter workable with both async/sync out-of-the-box
- Async RedisBucket built-in
- Contextmanager not available yet

Updates
* Add change log to sdist
* Improve test coverage
* Force check some bucket-keyword arguments