Fix nsfw black background

Signed-off-by: Raphael <oOraph@users.noreply.github.com>

app.py

@@ -94,7 +94,7 @@ def generate_background(prompt, num_inference_steps, height, width):
 
     if nsfw:
         LOG.info('NSFW detected, skipping')
-        background = np.zeros((height, width), dtype='uint8')
+        background = np.zeros((height, width, 3), dtype='uint8')
     else:
         background = np.array(background)
         # Convert RGB to BGR