fixed language

src/Symfony/Bridge/Doctrine/Validator/Constraints/UniqueEntityValidator.php

@@ -75,7 +75,7 @@ class UniqueEntityValidator extends ConstraintValidator
 
                 if (count($relatedId) > 1) {
                     throw new ConstraintDefinitionException(
-                        "Associated entities are not allowed have more than one identifier field to be " .
+                        "Associated entities are not allowed to have more than one identifier field to be " .
                         "part of a unique constraint in: " . $class->name . "#" . $fieldName
                     );
                 }