chore: relax HTTPX version upper bound, add support for zstd (#835)

### Description

- update `respx` to v0.22 with support `httpx` v 0.28
- add extra `zstd` for `httpx`, for support header {'accept-encoding:':
'zstd'}

### Issues

- closes #774

---------

Co-authored-by: Vlada Dusek <[email protected]>

Author: Mantisus