refactor bubble

src/Aquarium.h

@@ -80,7 +80,7 @@ public:
   [[nodiscard]] int getWidth() const { return width; }
   [[nodiscard]] int getHeight() const { return height; }
   void addFish();
-  void addBubble(float x, float y);
+  void addBubble(size_t x, size_t y);
   void addSeaweed();
   void addWaterline();
   void addCastle();