Merge pull request #265565 from aaronjheng/skl2onnx

python3Packages.skl2onnx: fix build

pkgs/top-level/python-packages.nix

···
 
   skidl = callPackage ../development/python-modules/skidl { };
 
-  skl2onnx = callPackage ../development/python-modules/skl2onnx {
-    protobuf = protobuf3;
-  };
+  skl2onnx = callPackage ../development/python-modules/skl2onnx { };
 
   sklearn-deap = callPackage ../development/python-modules/sklearn-deap { };