www/py-httpx-socks: Update to 0.5.1

• Remove 256527/225692-www_py-httpx-socks.diff that was added by mistake when this port was added to ports tree
• While here, re-format Makefile with portfmt

ChangeLog: https://github.com/romis2012/httpx-socks/releases/tag/v0.5.1
PR: 259356
Fixes: c87e99309f1a (www/py-httpx-socks: New port - Proxy (HTTP, SOCKS) transports for httpx)