Close files after copying in upload_file (#5679)

* fix: fix memory leak in upload_file

* fix: closing in another loop?

---------

Co-authored-by: Maxim Vlah <[email protected]>

Author: maximvlah

reflex/app.py

@@ -1926,6 +1926,13 @@ async def upload_file(request: Request):
                 )
             )
 
+        for file in files:
+            if not isinstance(file, StarletteUploadFile):
+                raise UploadValueError(
+                    "Uploaded file is not an UploadFile." + str(file)
+                )
+            await file.close()
+
         event = Event(
             token=token,
             name=handler,