Removed last dependencies on unittest. All tests are pytest-only.

tests/test_docs.py

@@ -30,7 +30,7 @@ assert filenames
 
 @pytest.mark.skipif(not has_docutils(), reason='docutils not installed')
 @pytest.mark.parametrize('filename', filenames)
-def test_rst_files_syntax(filename):
+def test_rst_file_syntax(filename):
     p = subprocess.Popen(
         ['rst2pseudoxml.py', '--report=1', '--exit-status=1', filename],
          stderr=subprocess.PIPE,