When pushing an update, update existing images where there's a difference

[samuel-emrys]

The current design means that if an image already exists on the wordpress site, it won't be update. This excludes the possibility of updating an image without manually deleting it first. Introduce the logic required to do a diff between the existing image size and the target image size to determine if it should be uploaded. A naive implementation would be to download every image and do a comparison:

import requests
response = requests.get(image_url)
existing_image_size = len(response.content)