Add "Source Code" and "Issue Tracker" links

Author: koutoftimer

setup.py

@@ -11,6 +11,8 @@
     url="https://github.com/scrapy/w3lib",
     project_urls=[
         "Documentation": "https://w3lib.readthedocs.io/en/latest/",
+        "Source Code": "https://github.com/scrapy/w3lib",
+        "Issue Tracker": "https://github.com/scrapy/w3lib/issues",
     ],
     packages=find_packages(exclude=("tests", "tests.*")),
     package_data={