Upgrade dependencies

[vyorkin]

Hi Yoshua,
Thank you for maintaining this crate!
In this PR I tried to carefully upgrade the dependencies to their latest versions and fix some clippy warnings.

Here is the list of updated crates:

• futures-lite (1.11.3 -> 2.6.0)
• http-types (2.10.0 -> 2.12.0)
• log (0.4.8 -> 0.4.27)
• memchr (2.3.3 -> 2.7.5)
• pin-project-lite (0.2.7 -> 0.2.16)
• async-channel (1.1.1 -> 2.5.0)
• async-std (1.6.0 -> 1.13.1)
• femme (2.0.0 -> 2.2.1)

I also had to update a few tests to use Box::pin for encoder, like this:
Here is what I mean:

let mut reader = decode(BufReader::new(Box::pin(encoder)));

Hopefully this is the right approach...

I split the changes into multiple commits to make the review easier.
Please let me know if anything needs improvement — I’m happy to help.

[vyorkin]

I removed Unpin but I'm not sure if this is correct.
Does reader: R actually need to implement Unpin...?
My understanding of pinning is quite limited :(

[vyorkin]

std::mem::take is just more concise and idiomatic (clippy suggested this change):
since String implements Default as an empty string, mem::take should replace this.buf with an empty string

[vyorkin]

I didn't find any usage of this buffer field