clear map and ptr after use

modules/background/tcgplayer.go

@@ -104,5 +104,8 @@ func getPriceFromAPI(pool *pool.Pool, api *apiact.TCGPlayer, groupid int) {
 
 	models.InsertCardPrice(insOpts)
 
+	cardMap = nil
+	prices = nil
+
 	return
 }