pythongh-97822: Fix http.server documentation reference to test() function

Author: Jason-Y-Z

Doc/library/http.server.rst

@@ -392,7 +392,7 @@ provides three different variants:
       contents of the file are output. If the file's MIME type starts with
       ``text/`` the file is opened in text mode; otherwise binary mode is used.
 
-      For example usage, see the implementation of the :func:`test` function
+      For example usage, see the implementation of the :source:`~http.server.test` function
       invocation in the :mod:`http.server` module.
 
       .. versionchanged:: 3.7