Fixing typo in DocTestRunner docs (pythonGH-112326)

(cherry picked from commit b3c2126)

Co-authored-by: Daniel Wysocki <dwysocki@users.noreply.github.com>

Author: dwysocki

Doc/library/doctest.rst

@@ -1475,7 +1475,7 @@ DocTestRunner objects
    For more information, see section :ref:`doctest-options`.
 
 
-   :class:`DocTestParser` defines the following methods:
+   :class:`DocTestRunner` defines the following methods:
 
 
    .. method:: report_start(out, test, example)