ci: fix goreleaser config
ci: fix goreleaser config

Currently goreleaser generated assets end up at URLs like:

   .../v0.3.0-beta.5/cue_0.3.0-beta.5_Linux_x86_64.tar.gz

Note the inconsistency between "v0.3.0-beta.5" and "0.3.0-beta.5"
(missing "v"), not to mention the use of mapped versions of GOOS and
GOARCH.

Fix this so that unity and others can rely on a more consistent download
URL format.

Tested locally that the right file names are generated.

Change-Id: Id4dacf7132af1a84d76ee3ac9a41540f7b2c06c5
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/8821
Reviewed-by: CUE cueckoo <0f32a827c9a5f00281f936ac78b5ef3ba80a954c@gmail.com>
Reviewed-by: Marcel van Lohuizen <a22d082192f3ccf984644a4f482781f4c2d65180@golang.org>

cuelang/cue