[5.0.x] Made cosmetic edits to code snippets reformatted with blacken-docs.

Backport of 0f694ce2ebce01356d48302c33c23902b4777537 from main.

docs/ref/forms/validation.txt

@@ -370,7 +370,7 @@ example::
                 # Only do something if both fields are valid so far.
                 if "help" not in subject:
                     raise ValidationError(
-                        "Did not send for 'help' in the subject despite " "CC'ing yourself."
+                        "Did not send for 'help' in the subject despite CC'ing yourself."
                     )
 
 In this code, if the validation error is raised, the form will display an

docs/ref/models/instances.txt

@@ -374,7 +374,7 @@ Then, ``full_clean()`` will check unique constraints on your model.
                         raise ValidationError(
                             {
                                 "status": _(
-                                    "Set status to draft if there is not a " "publication date."
+                                    "Set status to draft if there is not a publication date."
                                 ),
                             }
                         )