Updates for Actix4 latest beta (4.0.0-beta.20)

[poisson-fish]

Compiles, no warnings, seems to work fine.
Updated deps and migrated failure crate to thiserror.
Redis store crate is untouched and requires more work.
Don't hesitate to let me know if there's problems.

[kmindi]

@udidifier maybe a fork is needed? @TerminalWitchcraft seems to be not active anymore?

[tglman]

This looks good, hope a fork is not needed, let's see if @TerminalWitchcraft wake up :), otherwise happy to support the fork.

Or maybe is possible to handle over the crates.io crate

[jacob-pro]

This PR looks good to me, just needs changing to the actual actix 4 release version.

But if the crate is dead as a whole I think I'm going to look at moving to the actix-limitation which seems to be an officially maintained actix crate:
https://github.com/actix/actix-extras/tree/master/actix-limitation
Or maybe not, it looks incredibly lacking in functionality :(

[tglman]

Yep,

I was thinking about it, anyway I think we can port some functionality there and give up on this one, for myself i use the "memorystore" for the rate limiting, that should be seamless to port, and not add a big burden in maintenance, not sure about other implementations that require additional external server like memcache.

Regards

[jacob-pro]

@tglman For me the major issue with actix_limitation is as far as I can see there doesn't seem to be any way of providing your own function to retrieve the rate-limiting key from a request - instead it forces you to use cookies which is completely in-appropriate for my use case

[jacob-pro]

@tglman I have had a go at writing my own rate limiter that works with actix web 4:
https://github.com/jacob-pro/actix-extensible-rate-limit
Maybe it might be useful to you?

[tglman]

@jacob-pro saw it, trying to use it !