update docstring for `win_getpass` to reflect code changes (GH-24967)


The code was updated in
https://github.com/python/cpython/commit/0ec88b33d093db00ec68b220247681354a650f0c
but the docstring was left untouched.

=> updated the docstring to reflect the code changes
(cherry picked from commit d4222ea6b0bb3cf7d40f23b370dc9eea5f9b7004)

Co-authored-by: Jürgen Gmach <juergen.gmach@googlemail.com>
diff --git a/Lib/getpass.py b/Lib/getpass.py
index 6911f41..6970d8a 100644
--- a/Lib/getpass.py
+++ b/Lib/getpass.py
@@ -95,7 +95,7 @@ def unix_getpass(prompt='Password: ', stream=None):
 
 
 def win_getpass(prompt='Password: ', stream=None):
-    """Prompt for password with echo off, using Windows getch()."""
+    """Prompt for password with echo off, using Windows getwch()."""
     if sys.stdin is not sys.__stdin__:
         return fallback_getpass(prompt, stream)