Update Cart.php

[xujiongze]

Fix. An error occurred during the second remove. Check if the item still exists before removing

[github-actions]

Thank you for your pull request. However, you have submitted this PR on a Vanilo sub-module which is a read-only split of vanilo/framework. Please submit your PR on the https://github.com/vanilophp/framework repository.

Thanks!