Don't use deprecated distutils module.

[sebastic]

Overview

setup.py still uses the deprecated distutils which will be removed in Python 3.12.

From What’s New In Python 3.10:

The entire distutils package is deprecated, to be removed in Python 3.12. Its functionality for specifying package builds has already been completely replaced by third-party packages setuptools and packaging, and most other commonly used APIs are available elsewhere in the standard library (such as platform, shutil, subprocess or sysconfig). There are no plans to migrate any other functionality from distutils, and applications that are using other functions should plan to make private copies of the code. Refer to PEP 632 for discussion.

Because setup_requires is deprecated, PEP 517 (pyproject.toml) is used for the build time dependencies.

Contribution Agreement

(as per https://github.com/geopython/pywps/blob/master/CONTRIBUTING.rst#contributions-and-licensing)

• I'd like to contribute these changes to PyWPS. I confirm that my contributions to PyWPS will be compatible with the PyWPS license guidelines at the time of contribution.
• I have already previously agreed to the PyWPS Contributions and Licensing Guidelines

[coveralls]

Coverage: 81.35%. Remained the same when pulling 905208e on sebastic:no-distutils into d0bb978 on geopython:main.

[Zeitsperre]

Thanks for this contribution! I'll let @cehbrecht weigh in on whether we adopt PEP517 here.

[cehbrecht]

@sebastic thanks :)