bpo-34661: Fix test skipping call. (GH-9266)

(cherry picked from commit e78734d)

Co-authored-by: Benjamin Peterson <benjamin@python.org>

Lib/test/test_shutil.py

@@ -1125,7 +1125,7 @@ def test_unzip_zipfile(self):
             except subprocess.CalledProcessError as exc:
                 details = exc.output.decode(errors="replace")
                 if 'unrecognized option: t' in details:
-                    self.skip("unzip doesn't support -t")
+                    self.skipTest("unzip doesn't support -t")
                 msg = "{}\n\n**Unzip Output**\n{}"
                 self.fail(msg.format(exc, details))