Unassign keyup/change events before assigning

[NPC]

Hi,

To avoid multiple callback triggers if Sieve is initialized several times (otherwise no "destroy" is not really needed, which is nice), it makes sense to add this before the .on call:
settings.searchInput.off("keyup.sieve change.sieve");

PS I know I could create a PR for this, but I don't have time to figure it out, sorry.