move from httpx to httpx2

[vincentsarago]

https://github.com/pydantic/httpx2

we only use httpx in tests or notebook

[hrodmn]

Oof this is going to be messy - httpx2 🫠

It looks like rio-tiler also depends on httpx: https://github.com/cogeotiff/rio-tiler/blob/f76c42fe069ade784906b6dbc7aeaa4eccc3aa2d/pyproject.toml#L25

[vincentsarago]

will first do the rio-tiler switch then 🙏