fix error and update readme

backend/schemas.py

@@ -173,7 +173,6 @@ class ShopStats(BaseModel):
 
 # Update forward references
 BrandInShop.model_rebuild()
-ProductWithRelated.model_rebuild()
 
 # Related Products schemas
 class RelatedProductBase(BaseModel):
@@ -199,4 +198,7 @@ class ProductWithRelated(Product):
     related_products: List["Product"] = []
     
     class Config:
-        from_attributes = True 
+        from_attributes = True
+
+# Update forward references for classes that reference other classes
+ProductWithRelated.model_rebuild()