go-git: Improper single-quote escaping in go-git SSH transport

go-git is an extensible git implementation library written in pure Go. Prior to 5.19.1 and 6.0.0-alpha.4, go-git's SSH transport constructs the remote exec command by wrapping the repository path in single quotes without escaping single quotes embedded inside the path. A repository path containing a single quote can therefore break out of the quoted region in the exec command and be appended as additional shell tokens. This vulnerability is fixed in 5.19.1 and 6.0.0-alpha.4.