Update redis to 0.25.

[brocaar]

This updates Redis to 0.25 + updates aio::Connection to aio::MultiplexedConnection (as aio::Connection has been deprecated). I think it depends on the use-case if people want to use the same MultiplexedConnection for multiple queries, or want to create new MultiplexedConnections for each query (there are some queries that will block the MultiplexedConnection, in which case you might want to use multiple connections).

See also #305.

[bikeshedder]

This finally fixes the issues properly:

• Strange crosstalk(?} issue with deadpool redis #102
• Corrupt connections redis-rs/redis-rs#325

[bikeshedder]

I plan on releasing deadpool 0.11 soon including the updated deadpool-redis crate. I just added a follow up issue which can now be tackled:

• Add RecyclingMethod to deadpool-redis #307

Thanks for the PR! 😀 👍