Based on the issue description, I need to generate a patch for Django's `contrib/auth/validators.py` file. The issue is that the username validators use `^` and `$` anchors which allow trailing newlines. The fix is to use `\A` and `\Z` instead.

Here's the patch:

--- a/django/contrib/auth/validators.py
+++ b/django/contrib/auth/validators.py
@@ -7,7 +7,7 @@ from django.utils.translation import gettext_lazy as _
 
 @deconstructible
 class ASCIIUsernameValidator(validators.RegexValidator):
-    regex = r'^[\w.@+-]+$'
+    regex = r'\A[\w.@+-]+\Z'
     message = _(
         'Enter a valid username. This value may contain only English letters, '
         'numbers, and @/./+/-/_ characters.'
@@ -17,7 +17,7 @@ class ASCIIUsernameValidator(validators.RegexValidator):
 
 @deconstructible
 class UnicodeUsernameValidator(validators.RegexValidator):
-    regex = r'^[\w.@+-]+$'
+    regex = r'\A[\w.@+-]+\Z'
     message = _(
         'Enter a valid username. This value may contain only letters, '
         'numbers, and @/./+/-/_ characters.'