Throws a warning in php 7.3

Hello,

In some pages it shows a warning saying that the second parameter of method_exists() expects a strings but object received.
I checked the code and found that in inclues/frontend/general.php line 75 we have :
method_exists('is_empty', WC()->cart)
but the right order of parameters is: the object first and method name second
method_exists(WC()->cart, 'is_empty')
I fixed it in the code, but i hope it gets fixed in a future update.

Cheers,