Remove unused import and extraneous f prefix (#171)

* Remove unused import

* Remove extraneous `f` prefix

---------

Co-authored-by: Emil Sadek <[email protected]>

demo_gr.py

@@ -1,6 +1,5 @@
 import os
 import time
-from io import BytesIO
 import uuid
 
 import torch

src/flux/api.py

@@ -100,7 +100,7 @@ class ImageRequest:
 
             if name == "flux.1-dev":
                 if interval is not None:
-                    raise ValueError(f"Interval is not supported for flux.1-dev")
+                    raise ValueError("Interval is not supported for flux.1-dev")
             if name == "flux.1.1-pro":
                 if (
                     interval is not None