Update deprecated PHPCS config

Author: swissspidy

phpcs.xml.dist

@@ -19,7 +19,9 @@
 	<!-- Make sure we prefix everything in the global namespace. -->
 	<rule ref="WordPress.NamingConventions.PrefixAllGlobals">
 		<properties>
-			<property name="prefixes" type="array" value="preferred_languages" />
+			<property name="prefixes" type="array">
+				<element value="preferred_languages"/>
+			</property>
 		</properties>
 	</rule>