fix: clear old timers in useDeferredTrigger (#19)

With React 18, useEffect can run twice on mount in
strict mode (during development), which would lead
to a spurious timer remaining active. The timer always
needs to be cleared before a new one is set.

Author: steabert

src/useDeferredTrigger.ts

@@ -75,6 +75,7 @@ export const useDeferredTrigger = (
           // We need to wait at least a certain amount of time before
           // applying the delay. This can always be canceled by an update
           // that re-triggers this effect (as the timeout can be cleared).
+          clearTimeout(timeoutRef.current)
           timeoutRef.current = window.setTimeout(toggleFlag, scheduledDelay)
         }
       }