v2 - Always download latest version of go-sqlcmd

[zijchen]

From PR comments of #108

https://github.com/microsoft/go-sqlcmd/releases/latest links to the latest release, maybe we can grab the version from here.

Or go-sqlcmd adds a tag for "latest-version" and we can just use that download URL directly.

[github-actions]

This issue is idle because it has been open for 14 days with no activity.