A contract that has a stated end date in the contract is indeed something where you do not need to take any action. If you don't sign a new contract, that's it. It ran out. It ended.
Are you entitled to just simply decide not to renew the contract.
You are. That's what a contract with a fixed end date is.
I would not call that "ghosting" though. Ghosting is intentionally avoiding contact. Letting a contract run out is a normal thing. It's literally on the paper you signed when you started.
From a moral point of view, you owe it to yourself to have a new contract lined up with another employer, before the old one expires, so you are not unemployed and lose money in between. And personally, I would say don't lie. If they ask you to renew, just say "no thanks, I found another opportunity." If they don't ask before your last day, that's their problem, they signed a limited term contract with you, they should know what is in their own paperwork.