Update user.py

M in date format is minutes. m is for months.

lib/ansible/modules/system/user.py

@@ -243,7 +243,7 @@ class User(object):
     platform = 'Generic'
     distribution = None
     SHADOWFILE = '/etc/shadow'
-    DATE_FORMAT = '%Y-%M-%d'
+    DATE_FORMAT = '%Y-%m-%d'
 
     def __new__(cls, *args, **kwargs):
         return load_platform_subclass(User, args, kwargs)