add ghUpload for publishing to GitHub releases

[lrytz]

No description provided.

[lrytz]

it seems we have been publishing to s3 for every nightly. that was probably never intended? @SethTisue

didn't change that (yet) in this pr.

[lrytz]

Smoketest will need to be adjusted:

https://github.com/scala/scala-dist-smoketest/blob/2.13.x/scripts/jobs/release/smoketest#L45

[lrytz]

I tested it on a branch, it works. Uploaded a .zip from travis and a .msi from AppVeyor to https://github.com/scala/scala/releases/tag/v2.13.16.

[SethTisue]

it seems we have been publishing to s3 for every nightly. that was probably never intended? @SethTisue

I have no recollection of what that might have been about

(might it have been a hedge against our Artifactory getting corrupted...?)

[lrytz]

(might it have been a hedge against our Artifactory getting corrupted...?)

I really think this was just by accident...

[lrytz]

I'll backport this to 2.12, that branch is still on sbt 0.13.