Konova Code fix

* adds command sync_codelist
    * provides updating of all codes to the newest version (id)
    * must be run once on staging, can be dropped afterwards since the root for the problem has been resolved on the codelist management application

codelist/management/commands/update_codelist.py

@@ -6,7 +6,6 @@ Created on: 23.08.21
 
 """
 import requests
-from django.core.management import BaseCommand
 from xml.etree import ElementTree as etree
 
 from codelist.models import KonovaCode, KonovaCodeList