feature(brotli): bump mbrotli to 0.5.5

[Mnwa]

Motivation

v0.5.5 does a huge performance improvement for InputSize::Unknown. Especially it's helpful for async and sync IO because we don't know input size when IO stream was open.

Local benches (axum + tower + async-compression and wrk for load testing)

Scenario	Rust brotli	mbrotli 0.5.3	mbrotli 0.5.5
q4 json-1k	101k req/s	109k	123k
q4 html-128k	2,598 req/s	3,594	3,772
q4 json-1m	382 req/s	523–539	~540
q6 json-1k	51k req/s	45k	98k
q6 html-128k	1,489 req/s	2,085	2,182
q6 json-1m	175 req/s	255	280

[NobodyXu]

This is awesome!

However I don't think we need to bump it, just a cargo update on projects using our crate is good enough?

[Mnwa]

Yep, you're right. I can close this PR. It's really just a minimum version bump

[NobodyXu]

Thank you!

Happy to take a major version bump or a bugfix/new API to be used bump

[NobodyXu]

BTW, one thing we cab try in moving forward is, if --cfg async_compression_unstable is enabled, replace the default brotli impl with mbrotli

Or just do it locally and patch crates using it

That'd be an interesting test to see if it breaks anything