Fix typo

Author: zkdev

setup.cfg

@@ -26,7 +26,7 @@ classifiers =
 project_urls =
     Documentation = https://github3.readthedocs.io
     Changelog = https://github3.readthedocs.io/en/latest/release-notes/index.html
-    Source = https://github3.com/sigmavirus24/github3.py
+    Source = https://github.com/sigmavirus24/github3.py
     Released Versions = https://github.com/sigmavirus24/github3.py/tags
 requires_dist =
     requests>=2.0