Add upload script.

Author: dmjio

upload.nix

@@ -1,4 +1,8 @@
 with (import ./default.nix {});
 with pkgs.haskell.lib;
-buildFromSdist language-ecmascript
-
+let
+  tarball = sdistTarball language-ecmascript;
+in
+pkgs.writeScriptBin "upload" ''
+  ${pkgs.cabal-install}/bin/cabal upload ${tarball}/*.tar.gz --publish
+''