feat: added promocode getting by id, added likes add/delete, code refactoring

solution/apps/promo/migrations/0001_initial.py

@@ -1,4 +1,4 @@
-# Generated by Django 5.1.5 on 2025-01-23 17:54
+# Generated by Django 5.1.5 on 2025-01-24 18:26
 
 import apps.promo.validators
 import django.core.validators
@@ -86,7 +86,7 @@ class Migration(migrations.Migration):
                 ('user', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='liked_promocodes', to='user.user')),
             ],
             options={
-                'abstract': False,
+                'unique_together': {('promocode', 'user')},
             },
         ),
     ]