bump pibind11

[slayoo]

[slayoo]

@emmacware just reported that the following happens with CMake 4.0.1:

CMake Error at gitmodules/pybind11/CMakeLists.txt:8 (cmake_minimum_required):
  Compatibility with CMake < 3.5 has been removed from CMake.

  Update the VERSION argument <min> value.  Or, use the <min>...<max> syntax
  to tell CMake that the project requires at least <min> but has been updated
  to work with policies introduced by <max> or earlier.

  Or, add -DCMAKE_POLICY_VERSION_MINIMUM=3.5 to try configuring anyway.


gitmodules/pybind11/CMakeLists.txt:8: cmake_minimum_required(VERSION 3.4)