build: Updating mediawiki/mediawiki-codesniffer to 15.0.0

Change-Id: I4e5f3311af0f11905b8748be71b5fa8e5e5690a7

.phpcs.xml

@@ -2,6 +2,8 @@
 <ruleset>
 	<rule ref="./vendor/mediawiki/mediawiki-codesniffer/MediaWiki">
 		<exclude name="MediaWiki.Commenting.FunctionComment.MissingParamComment"/>
+		<exclude name="Squiz.Scope.MemberVarScope.Missing"/>
+		<exclude name="Squiz.Scope.MethodScope.Missing"/>
 	</rule>
 	<file>.</file>
 	<arg name="extensions" value="php,php5,inc"/>

composer.json

@@ -1,7 +1,7 @@
 {
 	"require-dev": {
 		"jakub-onderka/php-parallel-lint": "0.9.2",
-		"mediawiki/mediawiki-codesniffer": "14.1.0",
+		"mediawiki/mediawiki-codesniffer": "15.0.0",
 		"jakub-onderka/php-console-highlighter": "0.3.2",
 		"mediawiki/minus-x": "0.2.1"
 	},