Bump setuptools to 71.1.* and mark pkg_resources as obsolete (#12397)

stubs/setuptools/METADATA.toml

@@ -1,5 +1,9 @@
-version = "71.0.*"
+version = "71.1.*"
 upstream_repository = "https://github.com/pypa/setuptools"
+extra_description = """\
+If using `setuptools >= 71.1` *only* for `pkg_resources`,
+you don't need `types-setuptools` since `pkg_resources` is now typed.\
+"""
 
 [tool.stubtest]
 # darwin is equivalent to linux for OS-specific methods