Fix PHPCS error

Author: swissspidy

.maintenance/phpstorm.exclude-recursive-folders.php

@@ -55,11 +55,11 @@ protected static function has_project_iml() {
 		if ( is_file( self::get_project_iml_path() ) ) {
 			return; // already exists.
 		}
-		$modules_xml_content = <<<XML
+		$modules_xml_content = <<<'XML'
 <?xml version="1.0" encoding="UTF-8"?>
 <module type="WEB_MODULE" version="4">
 	<component name="NewModuleRootManager">
-		<content url="file://\$MODULE_DIR\$"/>
+		<content url="file://$MODULE_DIR$"/>
 		<orderEntry type="inheritedJdk" />
 		<orderEntry type="sourceFolder" forTests="false" />
 	</component>