add 'prpl_lesson_locale' filter to tests

Author: ilicfilip

tests/phpunit/test-class-page-types.php

@@ -74,6 +74,7 @@ public static function set_lessons_cache() {
 			[
 				'site'        => \get_site_url(),
 				'license_key' => \progress_planner()->get_license_key(),
+				'locale'      => apply_filters( 'prpl_lesson_locale', \get_locale() ),
 			],
 			$url
 		);