python3Packages.lightgbm: fix dll discovery (#451614)

pkgs/development/python-modules/lightgbm/default.nix

@@ -55,6 +55,18 @@ buildPythonPackage rec {
     hash = "sha256-yxxZcg61aTicC6dNFPUjUbVzr0ifIwAyocnzFPi6t/4=";
   };
 
+  # Patch dll search path to fix proper discovery of lib_lightgbm.so
+  #   Exception: Cannot find lightgbm library file in following paths:
+  # /nix/store/...-python3.13-lightgbm-4.6.0/lib/python3.13/site-packages/lib_lightgbm.so
+  # /nix/store/...-python3.13-lightgbm-4.6.0/lib/python3.13/site-packages/lightgbm/bin/lib_lightgbm.so
+  # /nix/store/...-python3.13-lightgbm-4.6.0/lib/python3.13/site-packages/lightgbm/lib/lib_lightgbm.so
+  postPatch = ''
+    substituteInPlace lightgbm/libpath.py \
+      --replace-fail \
+        'curr_path.parents[0] / "lib",' \
+        'curr_path.parents[1] / "lib",'
+  '';
+
   build-system = [
     scikit-build-core
   ];