Use sysconfig directly to determine python lib dir (#378)

The distutils package is deprecated and will be removed in Python 3.12.
We can achieve the same behavior using sysconfig directly.

Signed-off-by: Scott K Logan <[email protected]>

Author: cottsay

ament_cmake_python/ament_cmake_python-extras.cmake

@@ -44,9 +44,9 @@ macro(_ament_cmake_python_get_python_install_dir)
   if(NOT DEFINED PYTHON_INSTALL_DIR)
     # avoid storing backslash in cached variable since CMake will interpret it as escape character
     set(_python_code
-      "from distutils.sysconfig import get_python_lib"
       "import os"
-      "print(os.path.relpath(get_python_lib(prefix='${CMAKE_INSTALL_PREFIX}'), start='${CMAKE_INSTALL_PREFIX}').replace(os.sep, '/'))"
+      "import sysconfig"
+      "print(os.path.relpath(sysconfig.get_path('purelib', vars={'base': '${CMAKE_INSTALL_PREFIX}'}), start='${CMAKE_INSTALL_PREFIX}').replace(os.sep, '/'))"
     )
     get_executable_path(_python_interpreter Python3::Interpreter CONFIGURE)
     execute_process(