Fix transport compression

[lucascompython]

I didn't run cargo fmt --all because it formatted tens of files, maybe that should be done in another PR.
From my own testing, both zlib and zstd work now.
I also enabled the std feature of the zstd-safe crate so that we don't have to manually manage the buffer, hope that's ok.

Before these changes the decompressed buffer had 64KB of fixed size, so larger messages would be truncated and that caused the parsing errors.
The code before for zlib also assumed decompression happened in one call, but flate2::Decompress::decompress_vec doesn't manage the vec so it only writes as much as it can currently fit in it.

[KiloOscarSix]

fmt uses the nightly version, you'll need to install the nightly toolchain and then run cargo +nightly fmt

[lucascompython]

fmt uses the nightly version, you'll need to install the nightly toolchain and then run cargo +nightly fmt

Didn't know about that, oops.