Fix issue with get_file_size and S3 (#460)

Author: DavidMStraub

gramps_webapi/api/s3.py

@@ -121,8 +121,9 @@ def file_exists(self) -> bool:
 
     def get_file_size(self) -> int:
         """Return the file size in bytes."""
-        self.client.head_object(Bucket=self.bucket_name, Key=self.object_name)
-        response = self.client.head_object(Bucket=self.bucket_name, Key=key)
+        response = self.client.head_object(
+            Bucket=self.bucket_name, Key=self.object_name
+        )
         file_size = response["ContentLength"]
         return file_size