Merge pull request #83 from ImMin5/master

ix divided by zero error for calculating exchange rates

src/cloudforet/cost_analysis/manager/cost_manager.py

@@ -521,7 +521,7 @@ def _get_saved_cost(self, result: dict, cost: float) -> float:
 
         unit_price = self.retail_price_map[f"{meter_id}:{product_id}"]
 
-        if currency != "USD":
+        if currency != "USD" and quantity > 0:
             cost_in_billing_currency = self._convert_str_to_float_format(
                 result.get("costinbillingcurrency", 0.0)
             )