[TwigBundle] fixed XSD

src/Symfony/Bundle/TwigBundle/Resources/config/schema/twig-1.0.xsd

@@ -11,7 +11,6 @@
         <xsd:sequence>
             <xsd:element name="form" type="form" minOccurs="0" maxOccurs="1" />
             <xsd:element name="global" type="global" minOccurs="0" maxOccurs="unbounded" />
-            <xsd:element name="extension" type="xsd:string" minOccurs="0" maxOccurs="unbounded" />
         </xsd:sequence>
 
         <xsd:attribute name="auto-reload" type="xsd:string" />