Add typing classifier and changelog link

Author: A5rocks

setup.py

@@ -17,6 +17,7 @@
     project_urls={
         "Documentation": "https://outcome.readthedocs.io/en/latest/",
         "Chat": "https://gitter.im/python-trio/general",
+        "Changelog": "https://outcome.readthedocs.io/en/latest/history.html",
     },
     long_description=LONG_DESC,
     long_description_content_type='text/x-rst',
@@ -44,5 +45,6 @@
         'Programming Language :: Python :: 3.10',
         'Programming Language :: Python :: Implementation :: CPython',
         'Programming Language :: Python :: Implementation :: PyPy',
+        'Typing :: Typed',
     ],
 )