Fix typo in docs (GH-98863)

Author: yuvipanda

Doc/library/sys.rst

@@ -1178,7 +1178,7 @@ always available.
      string, which means the current working directory.
 
    To not prepend this potentially unsafe path, use the :option:`-P` command
-   line option or the :envvar:`PYTHONSAFEPATH` environment variable?
+   line option or the :envvar:`PYTHONSAFEPATH` environment variable.
 
    A program is free to modify this list for its own purposes.  Only strings
    should be added to :data:`sys.path`; all other data types are