Fix img2img with 1 step

Fixes #1.

Ideally, we should expose in the UI that one step only works with `strength` equal to `1`.

app.py

@@ -78,6 +78,8 @@ async def predict(init_image, prompt, strength, steps, seed=1231231):
         init_image = resize_crop(init_image)
         generator = torch.manual_seed(seed)
         last_time = time.time()
+        if steps == 1:
+            strength = 1.0
         results = i2i_pipe(
             prompt=prompt,
             image=init_image,