use scikit_build_core as build system

build.nix

@@ -0,0 +1,27 @@
+{
+  cmake,
+  ninja,
+  eigen,
+  python3Packages,
+}:
+python3Packages.buildPythonPackage {
+  pname = "slopefit";
+  version = "0.1.0";
+  pyproject = true;
+
+  buildInputs = [ eigen ];
+
+  nativeBuildInputs = [
+    cmake
+    ninja
+    python3Packages.scikit-build-core
+    python3Packages.nanobind
+  ];
+
+  buildPhase = ''
+    cd ..
+    pypaBuildPhase
+  '';
+
+  src = ./.;
+}