fix(security): warn on empty allowed_hosts and improve 421/403 response bodies - #2694

fix(security): warn on empty allowed_hosts and improve 421/403 response bodies#2694

BSmick6 wants to merge 4 commits into

modelcontextprotocol:mainmodelcontextprotocol/python-sdk:mainfrom

BSmick6:fix/transport-security-empty-allowlist-warningBSmick6/python-sdk:fix/transport-security-empty-allowlist-warningCopy head branch name to clipboard