[6.x] Tweak `cookie()` and `plainCookie()` return types (#941)
[6.x] Tweak `cookie()` and `plainCookie()` return types (#941)

* Fix return types

* Update InteractsWithCookies.php

Co-authored-by: Steve Bauman <2dbd1fcf3837bb456519a85e22380ecb0a40f52f@users.noreply.github.com>
Co-authored-by: Taylor Otwell <5d74ae093a16a00e5af127763f2dc7e13988f162@laravel.com>
laravel/dusk