[Form] fixed typo in XSD path

src/Symfony/Component/Form/Resources/config/validation.xml

@@ -2,7 +2,7 @@
 
 <constraint-mapping xmlns="http://symfony.com/schema/dic/constraint-mapping"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xsi:schemaLocation="http://symfony.com/schema/dic/constraint-mapping http://symfony.com/schema/dic/services/constraint-mapping-1.0.xsd">
+    xsi:schemaLocation="http://symfony.com/schema/dic/constraint-mapping http://symfony.com/schema/dic/constraint-mapping/constraint-mapping-1.0.xsd">
 
   <class name="Symfony\Component\Form\Field">
     <getter property="transformationSuccessful">