fix add video to dynamic playlist

apps/core/signals.py

 from django.conf import settings
 from django.dispatch import receiver
 from django.db.models.signals import post_save
+from django.contrib.contenttypes.models import ContentType
 
 from . import models, tasks, utils
 
@@ -18,5 +19,12 @@ def post_save_playlist(sender, instance, created, **kwargs):
         instance.mrss = f'{settings.DOMAIN_NAME}/api/playlist/{instance.id}/mrss'
         instance.save()
 
-    if instance.type == models.DYNAMIC:
-        utils.add_video_to_new_playlist(instance)
+
+@receiver(post_save, sender=models.TagToObject)
+def post_save_tags(sender, instance, created, **kwargs):
+    if created:
+        playlist_content_type = ContentType.objects.get_for_model(models.Playlist)
+        if instance.content_type == playlist_content_type:
+            playlist = models.Playlist.objects.get(id=instance.object_id)
+            if playlist.type == models.DYNAMIC:
+                utils.add_video_to_new_playlist(playlist)