I believe that the passport must be valid for the duration of the stay, but there is no particular requirement for it to be valid beyond that.

However, it is worth checking with your airline, for there have been cases in which passengers have been denied boarding because of a short period of validity remaining on their passport – whether this is due to errors or over-zealousness on the part of the check-in staff or to airline policy hardly matters when you can't get on the plane.