warning: Set PYBIND11_PYTHON_VERSION not PYTHON_VERSION

[rhaschke]

With pybind11 2.9.1 (shipped on Ubuntu 22.04), I get the following warning:

Warnings   << moveit_core:cmake /vol/sandbox/ros/logs/moveit_core/build.cmake.000.log                                                                               
TODO: Analyse and fix gcc's maybe-uninitialized warnings
CMake Warning at /usr/lib/cmake/pybind11/pybind11Tools.cmake:24 (message):
  Set PYBIND11_PYTHON_VERSION to search for a specific version, not
  PYTHON_VERSION (which is an output).  Assuming that is what you meant to do
  and continuing anyway.
Call Stack (most recent call first):
  /usr/lib/cmake/pybind11/pybind11Common.cmake:206 (include)
  /usr/lib/cmake/pybind11/pybind11Config.cmake:250 (include)
  /opt/ros/one/share/pybind11_catkin/cmake/pybind11_catkin.cmake:7 (find_package)
  /opt/ros/one/share/pybind11_catkin/cmake/pybind11_catkinConfig.cmake:224 (include)
  /opt/ros/one/share/catkin/cmake/catkinConfig.cmake:76 (find_package)
  CMakeLists.txt:64 (find_package)