Bug in ResponseLoggerMiddleware.php

As per the documentation the config file doesn't hold a config variable 'exclude', so it was throwing error in the foreach statement

```
$exclude = config('request-logger.exclude');
if($exclude){ //Added an if , if an exclude is coming as null so that error was not thrown
foreach($exclude as $path) {
if($request->is($path)) return true;
}
}
return false;
```

Please fix it.