release: disallow aliases

This will make hydra & ofborg ignore aliases when evluating

pkgs/top-level/release.nix

@@ -16,7 +16,7 @@
   # Strip most of attributes when evaluating to spare memory usage
 ,  scrubJobs ? true
   # Attributes passed to nixpkgs. Don't build packages marked as unfree.
-,  nixpkgsArgs ? { config = { allowUnfree = false; inHydra = true; }; }
+,  nixpkgsArgs ? { config = { allowUnfree = false; inHydra = true; allowAliases = false; }; }
 }:
 
 with import ./release-lib.nix { inherit supportedSystems scrubJobs nixpkgsArgs; };