トリガーをリセットするStatemacihneBehaviour

ResetTrigger.cs

using UnityEngine;

public class ResetTrigger : StateMachineBehaviour {

    [SerializeField]
    string triggerName;

    override public void OnStateExit(Animator animator, AnimatorStateInfo stateInfo, int layerIndex) {
        animator.ResetTrigger(triggerName);	
    }
}