message: Update index.tsx
  Allows uploading .webp thumbnails
diff: @@ -119,7 +119,7 @@ const BlockChangeThumbnail: React.FC<BlockChangeThumbnailProps> = ({
  <>
  <input
  type="file"
  - accept=".jpg,.jpeg,.gif,.png"
  + accept=".jpg,.jpeg,.gif,.png,.webp"
  ref={inputRef}
  style={{ display: 'none' }}
  onChange={onAddFile}
  