Use `date_creation` instead of `id` for sorting

.gitignore

 secrets.txt
-previous_id.txt
+previous_creation_date.txt
 venv
 __pycache__

bloomscroller.py

 import requests
 from mastodon import Mastodon
 import config
+import sys
 
 def get_images(album_api):
     return requests.get(album_api).json()['result']['images']
 
-def get_next_image(images, previous_id):
-    tail = [image for image in images if image['id']>previous_id]
-    return tail and sorted(tail, key=lambda image: image['id'])[0] or None
+def get_next_image(images, previous_creation_date):
+    tail = [image for image in images if image['date_creation']>previous_creation_date]
+    return tail and sorted(tail, key=lambda image: image['date_creation'])[0] or None
 
-def get_previous_id():
+def get_previous_creation_date():
    try: 
-       return int(json.load(open("previous_id.txt")))
+       return json.load(open("previous_creation_date.txt"))
    except Exception:
-       return 0
+       return ""
 
-def set_previous_id(previous_id):
-    json.dump(previous_id, open("previous_id.txt", "w"))
+def set_previous_creation_date(previous_creation_date):
+    json.dump(previous_creation_date, open("previous_creation_date.txt", "w"))
 
 def toot_next_image():
     mastodon = Mastodon(access_token="secrets.txt")
-    image = get_next_image(get_images(config.ALBUM_API), get_previous_id())
+    image = get_next_image(get_images(config.ALBUM_API), get_previous_creation_date())
     if image:
         if image['comment'] is None:
             image['comment'] = ""  # Better not mess up templates when no comment.
             media_ids=[media],
             visibility=config.TOOT_VISIBILITY,
             language=config.TOOT_LANGUAGE)
-        set_previous_id(image['id'])
+        set_previous_creation_date(image['date_creation'])
 
 if __name__=='__main__':
     toot_next_image()