python: Make it compatible with python3.12

Python 3.12 removes distutils so it's mandatory to use setuptools with
python >= 3.12.

This patch prints a message when trying to run the setup.py script with
a python >= 3.12 without setuptools and try to use the setuptools import
by default.

This patch also creates a new file, pyproject.toml [1], to prepare for
building in modern systems.

[1] https://peps.python.org/pep-0517/

Author: danigm

python/pyproject.toml

@@ -0,0 +1,3 @@
+[build-system]
+requires = ["setuptools"]
+build-backend = "setuptools.build_meta"

python/setup.py.in

@@ -5,11 +5,15 @@
 import sys, os, subprocess
 
 try:
-    import setuptools
+    from setuptools import setup, Extension
 except ImportError:
-    pass
-
-from distutils.core import setup, Extension
+    try:
+        # Using distutils, for python < 3.12
+        from distutils.core import setup, Extension
+    except ImportError:
+        # distutils is not present in python 3.12 and greater
+        print("setuptools is required for python >= 3.12")
+        sys.exit(1)
 
 # Below ROOT, we expect to find include, include/libxml2, lib and bin.
 # On *nix, it is not needed (but should not harm),