OrderSide top level does not add up

[xfoxawy]

adding new orders in the same level does not add up the amount

I have unit tests that are failing to show the case

t.Run("test adding multiple bid quantities to the same level ", func(t *testing.T) {
		var err error
		engine := NewLocalMatchingEngine("BTCUSD")
		updatesChan, _, ob, err := engine.SubscribeToOrderBook(ctx, "USDEGP")
		if err != nil {
			t.Fatal(err)
		}
		// check that the subscription channel receives a snapshot
		snapshot := <-updatesChan
		assert.NotNil(t, snapshot)

		// add levels to local matching engine
		var price float64 = 112.32
		res1, err := engine.CreateOrder(ctx, types.CreateOrderRequest{
			ExternalAccountId: "test-1234",
			Side:              types.BUY,
			Price:             &price,
			Quantity:          2.14,
		})
		if err != nil {
			t.Fatal(err)
		}
		assert.NotNil(t, <-updatesChan)
		assert.Equal(t, "OPEN", res1.Status)

		res2, err := engine.CreateOrder(ctx, types.CreateOrderRequest{
			ExternalAccountId: "test-1235",
			Side:              types.BUY,
			Price:             &price,
			Quantity:          1.24,
		})
		if err != nil {
			t.Fatal(err)
		}
		assert.NotNil(t, <-updatesChan)
		assert.Equal(t, "OPEN", res2.Status)

		
		assert.Equal(t, fpdecimal.FromFloat[float64](10000), ob.GetBestBid())
		assert.Equal(t, 1, ob.GetDepth(orderbook.Bid))
		assert.Equal(t, fpdecimal.FromFloat[float64](3.38), ob.GetBestVolume(orderbook.Bid))
		assert.Equal(t, decimal.NewFromFloat32(3.38), engine.orderbook.Depth().Bids()[0].Amount())
	})