assemble-distro: use specified tag, instead of hardcoding latest

Author: fingolfin

.github/workflows/assemble-distro.yml

@@ -93,6 +93,6 @@ jobs:
             github.rest.git.updateRef({
               owner: context.repo.owner,
               repo: context.repo.repo,
-              ref: "tags/latest",
+              ref: "tags/${{ env.RELEASE_TAG }}",
               sha: context.sha
             })