Adapt test to only run on Python 2, as it's redundant on Python 3.

setuptools/tests/test_build_meta.py

@@ -130,8 +130,9 @@ def test_prepare_metadata_for_build_wheel(build_backend):
     assert os.path.isfile(os.path.join(dist_dir, dist_info, 'METADATA'))
 
 
-def test_prepare_metadata_for_build_wheel_with_unicode(build_backend):
-    dist_dir = os.path.abspath('pip-dist-info')
+@pytest.mark.skipif('sys.version_info > (3,)')
+def test_prepare_metadata_for_build_wheel_with_str(build_backend):
+    dist_dir = os.path.abspath(str('pip-dist-info'))
     os.makedirs(dist_dir)
 
     dist_info = build_backend.prepare_metadata_for_build_wheel(dist_dir)