Fix GPU wheel build - use bundled pybind11

The pixi environment's pybind11 uses pybind11NewTools which requires
python_add_library from CMake's FindPython Development.Module component.
However, pixi's Python only provides the Interpreter component, causing
'Unknown CMake command python_add_library' error.

Solution: Use bundled pybind11 (MOMENTUM_USE_SYSTEM_PYBIND11=OFF) for GPU
Linux builds, which handles Python interface setup internally.

Author: jeongseok-meta

pyproject-pypi.toml.j2

@@ -151,7 +151,10 @@ cmake.args = [
     "-DMOMENTUM_ENABLE_SIMD=OFF",
     "-DCMAKE_CXX_SCAN_FOR_MODULES=OFF",
     "-DMOMENTUM_USE_SYSTEM_RERUN_CPP_SDK=OFF",
-    "-DMOMENTUM_USE_SYSTEM_PYBIND11=ON",
+    # Use bundled pybind11 to avoid CMake FindPython Development.Module requirement
+    # The pixi environment's pybind11 uses pybind11NewTools which requires python_add_library
+    # from CMake's FindPython, but pixi's Python only has Interpreter component
+    "-DMOMENTUM_USE_SYSTEM_PYBIND11=OFF",
 ]
 {% endif %}