change return type for Integration#expire_behavior
change return type for Integration#expire_behavior

meew0/discordrb,meew0/discordrb,megumisonoda/discordrb,VxJasonxV/discordrb,Roughsketch/discordrb,VxJasonxV/discordrb,megumisonoda/discordrb,Roughsketch/discordrb