Support RC versions in the go feature

[artificial-aidan]

By tweaking the go install script then go release candidates could be installed.

        if [ "${last_part_optional}" = "true" ]; then
            last_part="(${escaped_separator}[0-9]+|[rc0-9]+)?"
        else
            last_part="(${escaped_separator}[0-9]+|[rc0-9]+)"
        fi

[samruddhikhandale]

Thanks for the suggestion, adding to the backlog!