cbz2ebook: Refer constants by their new names

The old ones are deprecated and will be removed in Pillow 10.

cbz2ebook.py

@@ -33,7 +33,7 @@ def scaled_size(in_width, in_height, out_width, out_height):
 def process_image(im):
     # double pages (wider than high) should be rotated
     if im.width > im.height:
-        im = im.transpose(Image.ROTATE_90)
+        im = im.transpose(Image.Transpose.ROTATE_90)
 
     # convert to greyscale
     im = im.convert("L")
@@ -42,7 +42,7 @@ def process_image(im):
     if should_scale(im.width, im.height, args.width, args.height):
         im = im.resize(
             scaled_size(im.width, im.height, args.width, args.height),
-            resample=Image.LANCZOS,
+            resample=Image.Resampling.LANCZOS,
         )
 
     return im