Add all fields as optional.

backend/moonstreamapi/data.py

@@ -252,6 +252,6 @@ class DashboardCreate(BaseModel):
 
 
 class DashboardUpdate(BaseModel):
-    dashboard_id: Union[str,UUID]
-    name: str
-    subscriptions: List[DashboardMeta]
+    dashboard_id: Union[str, UUID]
+    name: Optional[str]
+    subscriptions: List[DashboardMeta] = Field(default_factory=list)