[HIGH] local file access in `Client:send` via manipulation of `$protocol` argument

PKSA-qbxp-nvx8-17hx GHSA-3fgr-xjr6-xqm8

Affected package: phpxmlrpc/phpxmlrpc

Affected version: <4.9.0

Reported by:
GitHub, FriendsOfPHP/security-advisories