Move declarative stuff out of setup.py to setup.cfg

So, why using setup.cfg if pyproject.toml is the new best thing
recommended everywhere? Well, quite a few of the fields we use with
setuptools are setuptools-specific and haven't been introduced as
keywords to pyproject.toml yet. There is a chance that these fields
could be added via a dedicated 'tool.setuptools' TOML section, but none
of it is officially documented and so it would be BETA at best anyway.
Let's not try our luck and use a declarative config file tailored
specifically to setuptools - setup.cfg. It's also unlikely we'd switch
from setuptools to something else in the near future given the nature
of building this project (i.e. building with C modules) and if so, it
would likely not be a PyPa recommended PEP-517 compliant build
system anyway, e.g. meson, so we're totally fine doing this.

Signed-off-by: Erik Skultety <eskultet@redhat.com>

setup.cfg

@@ -0,0 +1,20 @@
+[metadata]
+name = libvirt-python
+version = 9.5.0
+description = The libvirt virtualization API python binding
+long_description = file: README
+long_description_content_type = text/x-rst
+url = http://www.libvirt.org
+maintainer = Libvirt Maintainers
+maintainer_email = libvir-list@redhat.com
+license_files = COPYING
+classifiers =
+      Development Status :: 5 - Production/Stable
+      Intended Audience :: Developers
+      License :: OSI Approved :: GNU Lesser General Public License v2 or later (LGPLv2+)
+      Programming Language :: Python :: 3 :: Only
+
+[options]
+python_requires = >=3.6
+package_dir =
+    =build

setup.py

@@ -361,34 +361,17 @@ check_pkgcfg()
 
 _c_modules, _py_modules = get_module_lists()
 
-setup(name="libvirt-python",
-      version="9.5.0",
-      url="http://www.libvirt.org",
-      maintainer="Libvirt Maintainers",
-      maintainer_email="libvir-list@redhat.com",
-      description="The libvirt virtualization API python binding",
-      long_description=
-        """The libvirt-python package provides a module that permits applications
-written in the Python 3.x programming language to call the interface
-supplied by the libvirt library, to manage the virtualization capabilities
-of recent versions of Linux (and other OSes).""",
-      license="LGPLv2+",
-      ext_modules=_c_modules,
-      py_modules=_py_modules,
-      package_dir={
-          "": "build"
-      },
-      cmdclass={
-          "build_ext": my_build_ext,
-          "build_py": my_build_py,
-          "clean": my_clean,
-          "sdist": my_sdist,
-          "test": my_test
-      },
-      classifiers=[
-          "Development Status :: 5 - Production/Stable",
-          "Intended Audience :: Developers",
-          "License :: OSI Approved :: GNU Lesser General Public License v2 or later (LGPLv2+)",
-          "Programming Language :: Python :: 3",
-      ]
+setup(
+    ext_modules=_c_modules,
+    py_modules=_py_modules,
+    package_dir={
+        '': 'build'
+        },
+    cmdclass={
+        "build_ext": my_build_ext,
+        "build_py": my_build_py,
+        "clean": my_clean,
+        "sdist": my_sdist,
+        "test": my_test
+        },
 )