feat: implement stack

entity/Stack.py

@@ -0,0 +1,10 @@
+from entity.Piece import Piece
+from entity.Entity import Entity
+
+class Stack(Entity):
+
+    def __init__(self, color: str, border_color: str):
+        super().__init__([], color, border_color)
+
+    def add_piece(self, piece: Piece):
+        self.points += piece.points