add GitHub URL for PyPi (#1100)

* add GitHub URL for PyPi

* fix formatting

Author: andriyor

setup.py

@@ -68,6 +68,9 @@ def find_meta(meta):
         author=find_meta("author"),
         author_email=find_meta("email"),
         url=URI,
+        project_urls={
+            "Source": "https://github.com/pyca/pyopenssl",
+        },
         license=find_meta("license"),
         classifiers=[
             "Development Status :: 6 - Mature",