fix(bootstrap): remove duplicate / in path

tests/bootstrap.php

@@ -1,7 +1,7 @@
 <?php
 
 // First we need to load the composer autoloader, so we can use WP Mock
-require_once plugin_dir_path( __FILE__ ) . '/vendor/autoload.php';
+require_once plugin_dir_path( __FILE__ ) . 'vendor/autoload.php';
 
 // Bootstrap WP_Mock to initialize built-in features
 WP_Mock::bootstrap();