[Intl] [Workflow] fixes English grammar typos

Author: hhamon

MarkingStore/MethodMarkingStore.php

@@ -51,7 +51,7 @@ public function getMarking($subject)
         $method = 'get'.ucfirst($this->property);
 
         if (!method_exists($subject, $method)) {
-            throw new LogicException(sprintf('The method "%s::%s()" does not exists.', \get_class($subject), $method));
+            throw new LogicException(sprintf('The method "%s::%s()" does not exist.', \get_class($subject), $method));
         }
 
         $marking = $subject->{$method}();
@@ -81,7 +81,7 @@ public function setMarking($subject, Marking $marking, array $context = [])
         $method = 'set'.ucfirst($this->property);
 
         if (!method_exists($subject, $method)) {
-            throw new LogicException(sprintf('The method "%s::%s()" does not exists.', \get_class($subject), $method));
+            throw new LogicException(sprintf('The method "%s::%s()" does not exist.', \get_class($subject), $method));
         }
 
         $subject->{$method}($marking, $context);