Fix failing test

Each test now runs with a clean slate as PriceBuilderProcessPoENinjaResponse was being affected by previous tests

Author: LocalIdentity

spec/System/TestTradeQueryCurrency_spec.lua

@@ -1,5 +1,9 @@
 describe("TradeQuery Currency Conversion", function()
-	local mock_tradeQuery = new("TradeQuery", { itemsTab = {} })
+	local mock_tradeQuery
+
+	before_each(function()
+		mock_tradeQuery = new("TradeQuery", { itemsTab = {} })
+	end)
 
 	-- test case for commit: "Skip callback on errors to prevent incomplete conversions"
 	describe("FetchCurrencyConversionTable", function()