Add changelog URL to package metadata

When Renovate bot creates an automated pull request to update Poetry, it can automatically include the link to changelog so it's easier to find out what changed.

Author: intgr

setup.py

@@ -78,6 +78,9 @@
     version=supervisor_version,
     license='BSD-derived (http://www.repoze.org/LICENSE.txt)',
     url='http://supervisord.org/',
+    project_urls={
+        'Changelog': 'http://supervisord.org/changes.html',
+    },
     description="A system for controlling process state under UNIX",
     long_description=README + '\n\n' + CHANGES,
     classifiers=CLASSIFIERS,
@@ -87,7 +90,7 @@
     install_requires=requires,
     extras_require={
         'testing': testing_extras,
-        },
+    },
     tests_require=tests_require,
     include_package_data=True,
     zip_safe=False,