Revert "setup.cfg: remove "Source" and "Tracker" project URLs"

This reverts commit f44db8d.

Apparently, if none of your `project_urls` link to the GitHub repo, the
"GitHub Statistics" section disappears. Weird, but OK.

Author: generalmimon

setup.cfg

@@ -6,6 +6,8 @@ author_email = [email protected]
 url = https://kaitai.io
 project_urls =
     Documentation = https://doc.kaitai.io/
+    Source = https://github.com/kaitai-io/kaitai_struct_python_runtime
+    Tracker = https://github.com/kaitai-io/kaitai_struct_python_runtime/issues
     Gitter = https://gitter.im/kaitai_struct/Lobby
 description = Kaitai Struct declarative parser generator for binary data: runtime library for Python
 long_description = file: README.md