SPM support basic auth for non-git binary dependency hosts

[tallariel (Ariel Elkin)]

@theRealRobG

I've found that GitHub API will disregard a file extension if you add it, so you can just append .zip to the URL declaration to appease SPM (though perhaps the need to do this should also be revised).

I tried doing this and Xcode 13.2 produced the following error:

failed downloading 'https://api.github.com/repos/{owner}/{repo}/releases/assets/{release_id}.zip' which is required by binary target 'TargetName': badResponseStatusCode(404)