jsonnet: fix evaluation

pkgs/development/compilers/jsonnet/default.nix

···
   meta = {
     description = "Purely-functional configuration language that helps you define JSON data";
     maintainers = [ lib.maintainers.benley ];
-    license = lib.licenses.apache;
+    license = lib.licenses.asl20;
     homepage = https://github.com/google/jsonnet;
   };
 }