gix-transport indirect code execution via malicious username

gitoxide is a pure Rust implementation of Git. `gix-transport` does not check the username part of a URL for text that the external `ssh` program would interpret as an option. A specially crafted clone URL can smuggle options to SSH. The possibilities are syntactically limited, but if a malicious clone URL is used by an application whose current working directory contains a malicious file, arbitrary code execution occurs. This is related to the patched vulnerability GHSA-rrjw-j4m2-mf34, but appears less severe due to a greater attack complexity. This issue has been patched in versions 0.35.0, 0.42.0 and 0.62.0.