Fix discovery of python

setup.py

@@ -144,6 +144,7 @@ def build_extension(self, ext: CMakeExtension) -> None:
             f"-DCMAKE_LIBRARY_OUTPUT_DIRECTORY={extdir}{os.sep}",
             f"-DCMAKE_BUILD_TYPE={cfg}",  # not used on MSVC, but no harm
             "-DCMAKE_UNITY_BUILD=ON",
+            f"-DPython_EXECUTABLE={sys.executable}",
         ]
 
         # Pile all .so in one place and use $ORIGIN as RPATH