Entries can optionally be filtered by airing status (airing, finished, planned)

Motivation for changes:

The lack of this filter was causing conflict with my config when tracking watch progress of anime that has finished airing with MAL, since I usually get these from a batch manually.

Detailed changes:

Added new optional parameter airing_status to further filter entries as finished, airing and\or planned (also shown as Not Yet Aired on MAL)

Config usage if relevant (new plugin or updated schema):

    Syntax:
    my_anime_list:
      username: <value>
      status:
        - <watching|completed|on_hold|dropped|plan_to_watch>
        - <watching|completed|on_hold|dropped|plan_to_watch>
        ...
      airing_status:
        - <airing|finished|planned>
        - <airing|finished|planned>
        ...
      type:
        - <series|ova...>