xgboost: fix license

Looks like `nix-env -qaP --drv-path` is not enough and one need to
either add `--json` too to catch problems like this... or just use
`nox-review wip`.

pkgs/development/libraries/xgboost/default.nix

@@ -23,7 +23,7 @@ stdenv.mkDerivation rec {
   meta = with stdenv.lib; {
     description = "Scalable, Portable and Distributed Gradient Boosting (GBDT, GBRT or GBM) Library";
     homepage = "https://github.com/dmlc/xgboost";
-    license = licenses.apl20;
+    license = licenses.asl20;
     platforms = platforms.linux;
     maintainers = with maintainers; [ abbradar ];
   };