Upgrade redis to 0.22

[Joel Natividad]

and possibly use the optional ahash feature which gives a 7-10% performance bump:

https://github.com/redis-rs/redis-rs/blob/1b3f8ad0e1ebfe4e7d81563559c1e743acc5e806/redis/src/lib.rs#L60

[James Kominick]

updated in v0.40.0. The ahash feature can be enabled with the redis_ahash feature