fix: use str instead of float to preserve precision in large numerical values

Author: 1yam

src/aleph/sdk/query/responses.py

@@ -77,5 +77,5 @@ class MessagesResponse(PaginationResponse):
 class PriceResponse(BaseModel):
     """Response from an aleph.im node API on the path /api/v0/price/{item_hash}"""
 
-    required_tokens: float
+    required_tokens: str
     payment_type: str