Add language line for image dimensions validation rule

Signed-off-by: crynobone <crynobone@gmail.com>

fixture/resources/lang/en/validation.php

@@ -34,6 +34,7 @@
     'different'            => 'The :attribute and :other must be different.',
     'digits'               => 'The :attribute must be :digits digits.',
     'digits_between'       => 'The :attribute must be between :min and :max digits.',
+    'dimensions'           => 'The :attribute has invalid image dimensions.',
     'distinct'             => 'The :attribute field has a duplicate value.',
     'email'                => 'The :attribute must be a valid email address.',
     'exists'               => 'The selected :attribute is invalid.',