fix: DEV-2665: Fix django migrations warning (#2543)

Author: triklozoid

label_studio/core/settings/base.py

@@ -100,6 +100,8 @@
 DATABASES_ALL['default'] = DATABASES_ALL[DJANGO_DB_POSTGRESQL]
 DATABASES = {'default': DATABASES_ALL.get(get_env('DJANGO_DB', 'default'))}
 
+DEFAULT_AUTO_FIELD = 'django.db.models.AutoField'
+
 LOGGING = {
     'version': 1,
     'disable_existing_loggers': False,