Redirect to URL where the Impersonation was triggered not working

Firstly, thanks for the great plugin.
Unfortunately I found a bug, where the leave method doesn't redirect to the page as intended:

````

if (session()->has('laravel-impersonate:leave_redirect_to')) {
$routeName = session('laravel-impersonate:leave_redirect_to');
session()->forget('laravel-impersonate:leave_redirect_to');
}
````
The above code is great, but it appears that the session parameter has never been set.

I'm creating a pull request to fix that issue and will refer this issue to it. Please merge in a timely manner, so I don't have to implement my fork into production.

Thanks in advance. PR coming soon