Stop skipping setuptools in vendoring upgrades

This ensures that we don't miss out on improvements and fixes in
newer versions of setuptools.

Author: pradyunsg

noxfile.py

@@ -199,9 +199,6 @@ def pinned_requirements(path: Path) -> Iterator[Tuple[str, str]]:
 
     vendor_txt = Path("src/pip/_vendor/vendor.txt")
     for name, old_version in pinned_requirements(vendor_txt):
-        if name == "setuptools":
-            continue
-
         # update requirements.txt
         session.run("vendoring", "update", ".", name)