Support zstd encoding

[iamnotaprogrammer]

I suggest to add zstd(https://github.com/facebook/zstd) as brotli/gzip encoding methods.
Zstd has a great speed and compression ratio tradeoff.

[lovelydinosaur]

Useful ways to gauge if this would be valuable for us...

• Can you point to a URL that supports zstd?
• Which browsers support zstd?
• Which HTTP clients support zstd? (Python or other languages)

[Zaczero]

zstd is now supported by Chromium-based browsers: https://caniuse.com/zstd

[karpetrosyan]

Useful ways to gauge if this would be valuable for us...

* Can you point to a URL that supports zstd?

* Which browsers support zstd?

* Which HTTP clients support zstd? (Python or other languages)

• URL that supports zstd
  https://www.facebook.com 😄

• Which browsers support zstd?
  https://chromestatus.com/feature/6186023867908096

• Which HTTP clients support zstd?
  curl support: https://everything.curl.dev/internals/content-encoding
  urllib3 support: https://urllib3.readthedocs.io/en/stable/advanced-usage.html#zstandard-encoding

[lovelydinosaur]

Okay worth escalating

[mbeijen]

I've added a PR: #3139

[mbeijen]

So, httpx now supports zstd encoding in the master branch - not yet in a release. I guess this discussion can be closed?

[lovelydinosaur]

Ah, yep we can mark it as answered.

I'd typically prefer that we get really consistent process-wise around the workflow of...

• Discussion phase.
• Escalate to issue #....
• Pull request. (with closes #... included in description.)