Update backup.php

use DB_CONNECTION env var as default database connection

Author: Sairahcaz

config/backup.php

@@ -77,7 +77,7 @@
              * For a complete list of available customization options, see https://github.com/spatie/db-dumper
              */
             'databases' => [
-                'mysql',
+                env('DB_CONNECTION', 'mysql'),
             ],
         ],