message: Fix cmake when pybind11 was already added
diff: @@ -155,6 +155,7 @@ else()
  endif()
  if (ENOKI_ENABLE_PYTHON)
  + if (NOT TARGET pybind11::module)
  if (SKBUILD)
  execute_process(
  COMMAND
  @@ -174,6 +175,7 @@ if (ENOKI_ENABLE_PYTHON)
  PYBIND11_FINDPYTHON PYBIND11_PYTHON_VERSION PYBIND11_WERROR
  ENOKI_PYBIND11_DIR)
  endif()
  + endif()
  message(STATUS "Enoki: building the Python plugin.")
  add_subdirectory(src/python)
  