canto-saas-api: Authenticated API requests can be redirected via unencoded path variables

Summary

canto-saas-api is a PHP library for interacting with the Canto SaaS API. Prior to version 3.0.0, Request::buildRequestUrl() joins values returned by Request::getPathVariables() without encoding individual path segments, including the scheme and contentId values used by GetContentDetailsRequest. When a consuming application supplies an untrusted path variable value, path traversal sequences, query delimiters, or fragment delimiters can change the destination endpoint before AbstractEndpoint::sendRequest() attaches the configured authentication token. An attacker who controls that path variable value through the consuming application can cause unintended reads or writes with the configured application's privileges on the same Canto instance, but applications that pass only trusted and validated identifiers are not exploitable. This issue is fixed in version 3.0.0.