Build: use same version of setuptools when using system_packages (#10287)

The same version installed before needs to match here.

Fixes #10285

Author: stsewd

readthedocs/doc_builder/python_environments.py

@@ -248,10 +248,8 @@ def install_core_requirements(self):
             # even if it is already installed system-wide (and
             # --system-site-packages is used)
             cmd.append('-I')
-            # If this flag is present,
-            # we need to cap setuptools again.
-            # See https://github.com/readthedocs/readthedocs.org/issues/8775
-            requirements.append('setuptools<58.3.0')
+            # The same version of setuptools used above needs to be used here.
+            requirements.append(setuptools_version)
         cmd.extend(requirements)
         self.build_env.run(
             *cmd,

readthedocs/rtd_tests/tests/test_doc_building.py

@@ -451,7 +451,7 @@ def test_install_core_requirements_sphinx_system_packages_caps_setuptools(self,
             "sphinx-rtd-theme",
             "readthedocs-sphinx-ext",
             "jinja2<3.1.0",
-            "setuptools<58.3.0",
+            "setuptools",
         ]
 
         self.assertEqual(self.build_env_mock.run.call_count, 2)