Fix mypy heisenfailure on Windows

Author: oschwald

tests/reader_test.py

@@ -522,7 +522,6 @@ def test_closed_metadata(self) -> None:
             self.assertIsNotNone(metadata, "pure Python implementation returns value")
 
     if os.name != "nt":
-
         def test_multiprocessing(self):
             self._check_concurrency(self.mp.Process)
 
@@ -543,6 +542,7 @@ def lookup(pipe) -> None:
                 except:
                     pipe.send(0)
                 finally:
+                    # type: ignore[attr-defined]
                     if worker_class is self.mp.Process:
                         reader.close()
                     pipe.close()