Update setup.py to replace distutils.core by setuptools

Fix #19

CHANGELOG.md

@@ -33,6 +33,11 @@ In this release, test coverage is 79%.
 
 🛠️ Bug fixes:
 
+* [Issue #19](https://github.com/PlotPyStack/PlotPy/issues/19) - Fix `distutils`
+  deprecation in setup.py: replaced `distutils.core` by `setuptools` in the setup.py
+  script to avoid the deprecation warning when building the package with Python 3.10
+  and 3.11, and to ensure compatibility with earlier Python versions (PlotPy is already
+  compatible with the most recent Python versions: this only concerns the build system)
 * Fix cyclic import in `plotpy.tools` module:
   * Some tools in `plotpy.tools` subpackage were importing the `plotpy.plot` module,
     which was importing the `plotpy.tools` module, causing a cyclic import issue

setup.py

@@ -4,12 +4,11 @@
 import os.path as osp
 import platform
 import sys
-from distutils.core import setup
 
 import numpy
 from Cython import __version__ as __cython_version__
 from Cython.Compiler import Main
-from setuptools import Distribution, Extension
+from setuptools import Distribution, Extension, setup
 
 LIBNAME = "plotpy"
 SRCPATH = osp.join(".", "src")