fix(models): Update grouped_by type to allow None in ProjectedGroupedUsage and GroupedUsage classes (#344)

* fix(models): Update `grouped_by` type to allow None in ProjectedGroupedUsage and GroupedUsage classes

* fix(models): Change `grouped_by` type to use `Optional[str]` for python 3.9 support

Author: gangeshwark

lago_python_client/models/customer_projected_usage.py

@@ -41,7 +41,7 @@ class ProjectedGroupedUsage(BaseModel):
     events_count: int
     units: str
     projected_units: str
-    grouped_by: Dict[str, str]
+    grouped_by: Dict[str, Optional[str]]
     filters: List[ProjectedChargeFilterUsage]
     pricing_unit_details: Optional[PricingUnitDetails]
 

lago_python_client/models/customer_usage.py

@@ -37,7 +37,7 @@ class GroupedUsage(BaseModel):
     amount_cents: int
     events_count: int
     units: str
-    grouped_by: Dict[str, str]
+    grouped_by: Dict[str, Optional[str]]
     filters: List[ChargeFilterUsage]
     pricing_unit_details: Optional[PricingUnitDetails]