fix: handle small input images

If input images didn't need resizing because they were already smaller than max width/height then they didn't get normalized to a multiple of 64.  This caused an exception like the following:

```Sizes of tensors must match except in dimension 1. Expected size 4 but got size 3 for tensor number 1 in the list.
```

Makefile

@@ -26,7 +26,7 @@ init: require_pyenv  ## Setup a dev environment for local development.
 
 af: autoformat  ## Alias for `autoformat`
 autoformat:  ## Run the autoformatter.
-	@pycln . --all --quiet
+	@pycln . --all --quiet --extend-exclude __init__\.py
 	@isort --atomic --profile black .
 	@black .
 

imaginairy/img_utils.py

@@ -12,10 +12,17 @@ from imaginairy.utils import get_device
 def pillow_fit_image_within(image: PIL.Image.Image, max_height=512, max_width=512):
     image = image.convert("RGB")
     w, h = image.size
+    resize_ratio = 1
     if w > max_width or h > max_height:
         resize_ratio = min(max_width / w, max_height / h)
+    elif w < max_width and h < max_height:
+        # it's smaller than our target image, enlarge
+        resize_ratio = max(max_width / w, max_height / h)
+
+    if resize_ratio != 1:
         w, h = int(w * resize_ratio), int(h * resize_ratio)
-        w, h = map(lambda x: x - x % 64, (w, h))  # resize to integer multiple of 64
+    w, h = map(lambda x: x - x % 64, (w, h))  # resize to integer multiple of 64
+    if (w, h) != image.size:
         image = image.resize((w, h), resample=Image.Resampling.LANCZOS)
     return image