GHSA-94PJ-82F3-465W Guzzle: Proxy-Authorization headers can be sent to origin servers

Impact In affected versions, the built-in cURL handlers CurlHandler and CurlMultiHandler put every first-class request header in cURL's origin header list CURLOPTHTTPHEADER. These handlers are the default when the PHP cURL extension is available. They move Proxy-Authorization to the proxy-only li...