minor modification

- sys.__stdout__ is the value stdout had at the beginning of the Python program.
- instead, let's reconnect to the stdout stream we used immediately before we
  redirected into the StringIO object. This should be (mildly) more robust.

tests.py

@@ -102,10 +102,11 @@ def test_run_method(tmp_path):
     # check that ##-08 is printed when run(["echo", "Good Bye, world!"]) is run
     # the 8 in ##-08 is present because
     # this is the 8th run of the `run` function
+    stdout_original = sys.stdout  # preserve current stdout stream
     captured_output = StringIO()  # create an in-memory file-like object.
     sys.stdout = captured_output  # redirect stdout to the file
     run(["echo", "Good Bye, world!"])
-    sys.stdout = sys.__stdout__  #  restores the original stdout
+    sys.stdout = stdout_original  #  restores the original stdout
     assert "##-08" in captured_output.getvalue()