nat_and_induction_in_lean: update to lean 3.18.4
nat_and_induction_in_lean: update to lean 3.18.4

avigad/logic_and_proof,avigad/logic_and_proof,leanprover/logic_and_proof,leanprover/logic_and_proof,avigad/logic_and_proof,leanprover/logic_and_proof