feat: item

- Create item.py
- Add update to remove expired items
- Add item settings for spawn interval, despawn timer, and size

src/item.py

@@ -0,0 +1,19 @@
+import pygame
+import random
+from src.settings import (
+    ITEM_SPAWN_INTERVAL, ITEM_SHOPPING_TIMER, ITEM_SIZE,
+    COLOR_HP_BAR_YELLOW, COLOR_HP_BAR_BG
+)
+
+# remove expired items
+def update(self, room_rect, blocked_rects):
+    now = pygame.time.get_ticks()
+
+    remaining_items = []
+
+    for item in self.items:
+        if item.is_expired() == False:
+            remaining_items.append(item)
+
+        # replace the old list with the new temp_list
+        self.items = remaining_items