fix: validate key instead of value od fallback default pool

program/models.py

@@ -625,8 +625,8 @@ def validate_fallback_pools(value):
 
 
 def validate_fallback_default_pool(value):
-    if value not in RadioSettings.objects.first().fallback_pools.values():
-        raise DjangoValidationError(f"Pool '{value}' does not exist in fallback pools.")
+    if value not in RadioSettings.objects.first().fallback_pools.keys():
+        raise DjangoValidationError(f"Pool key '{value}' does not exist in fallback pools.")
 
 
 class RadioSettings(models.Model):