Build failure with python3.12

[remicollet]

From Fedora 39 which has python3.12 by default
https://bugzilla.redhat.com/show_bug.cgi?id=2226397

Traceback (most recent call last):
  File "/builddir/build/BUILD/rnp-v0.17.0/src/tests/cli_tests.py", line 14, in <module>
    from cli_common import (file_text, find_utility, is_windows, list_upto,
  File "/builddir/build/BUILD/rnp-v0.17.0/src/tests/cli_common.py", line 2, in <module>
    import distutils.spawn
ModuleNotFoundError: No module named 'distutils'
CMake Error at src/tests/CMakeLists.txt:237 (message):
  Failed to retrieve test suite list for cli_tests

Switching to setuptools._distutils.spawn seems a working solution, but is only working with recent python versions
Tested on RHEL-9 with python 3.9 and setuptools 53.0

[ni4]

@remicollet Thanks for reporting and fix suggestion! PR #2113 is aimed to fix this issue.