Remove timer when scroll finished

If smooth scrolling has reached its target, scroll_animation_tick()
clears the timer ID in the animation object. However, the timer
was not removed, which resulted in the timers potentially accumulating
and preventing the creation of new timers eventually. This caused smooth
scrolling to stop working in the terminal.

kitty/window.py

@@ -2461,6 +2461,7 @@ class Window:
         if progress >= 1.0:
             # Ensure we land exactly on a line boundary with pixel_scroll_offset_y = 0
             self.screen.scroll_to_absolute(max(0, a.start_scrolled_by - a.total))
+            remove_timer(a.timer)
             a.timer = 0
         else:
             # Use absolute positioning to avoid pixel rounding errors from incremental fractional scrolls