bpo-38347: Use double quotes instead of single ones

Co-Authored-By: Victor Stinner <[email protected]>

Author: rpluem

Lib/test/test_tools/test_pathfix.py

@@ -55,7 +55,7 @@ def test_recursive(self):
         tmpdir = support.TESTFN + '.d'
         self.addCleanup(support.rmtree, tmpdir)
         os.mkdir(tmpdir)
-        expected_stderr = f'recursedown(\'{os.path.basename(tmpdir)}\')\n'
+        expected_stderr = f"recursedown('{os.path.basename(tmpdir)}')\n"
         self.assertEqual(
             self.pathfix(
                 '#! /usr/bin/env python',