[10.x] Standardise "must" in translations (#45989)

* Use "must" instead of "may"

* Standardises language to use X must Y.

Author: timacdonald

src/Illuminate/Translation/lang/en/validation.php

@@ -15,7 +15,7 @@
 
     'accepted' => 'The :attribute field must be accepted.',
     'accepted_if' => 'The :attribute field must be accepted when :other is :value.',
-    'active_url' => 'The :attribute field is not a valid URL.',
+    'active_url' => 'The :attribute field must be a valid URL.',
     'after' => 'The :attribute field must be a date after :date.',
     'after_or_equal' => 'The :attribute field must be a date after or equal to :date.',
     'alpha' => 'The :attribute field must only contain letters.',
@@ -34,9 +34,9 @@
     'boolean' => 'The :attribute field must be true or false.',
     'confirmed' => 'The :attribute field confirmation does not match.',
     'current_password' => 'The password is incorrect.',
-    'date' => 'The :attribute field is not a valid date.',
+    'date' => 'The :attribute field must be a valid date.',
     'date_equals' => 'The :attribute field must be a date equal to :date.',
-    'date_format' => 'The :attribute field does not match the format :format.',
+    'date_format' => 'The :attribute field must match the format :format.',
     'decimal' => 'The :attribute field must have :decimal decimal places.',
     'declined' => 'The :attribute field must be declined.',
     'declined_if' => 'The :attribute field must be declined when :other is :value.',
@@ -45,8 +45,8 @@
     'digits_between' => 'The :attribute field must be between :min and :max digits.',
     'dimensions' => 'The :attribute field has invalid image dimensions.',
     'distinct' => 'The :attribute field has a duplicate value.',
-    'doesnt_end_with' => 'The :attribute field may not end with one of the following: :values.',
-    'doesnt_start_with' => 'The :attribute field may not start with one of the following: :values.',
+    'doesnt_end_with' => 'The :attribute field must not end with one of the following: :values.',
+    'doesnt_start_with' => 'The :attribute field must not start with one of the following: :values.',
     'email' => 'The :attribute field must be a valid email address.',
     'ends_with' => 'The :attribute field must end with one of the following: :values.',
     'enum' => 'The selected :attribute is invalid.',
@@ -67,7 +67,7 @@
     ],
     'image' => 'The :attribute field must be an image.',
     'in' => 'The selected :attribute is invalid.',
-    'in_array' => 'The :attribute field does not exist in :other.',
+    'in_array' => 'The :attribute field must exist in :other.',
     'integer' => 'The :attribute field must be an integer.',
     'ip' => 'The :attribute field must be a valid IP address.',
     'ipv4' => 'The :attribute field must be a valid IPv4 address.',
@@ -134,7 +134,7 @@
     'required_with_all' => 'The :attribute field is required when :values are present.',
     'required_without' => 'The :attribute field is required when :values is not present.',
     'required_without_all' => 'The :attribute field is required when none of :values are present.',
-    'same' => 'The :attribute field and :other must match.',
+    'same' => 'The :attribute field must match :other.',
     'size' => [
         'array' => 'The :attribute field must contain :size items.',
         'file' => 'The :attribute field must be :size kilobytes.',