Fix modify_site workflow where a site was modified to contain the same information as before

gso/utils/types/unique_field.py

 """An input field that must be unique in the database."""
 
+from functools import partial
 from typing import Annotated, TypeVar
 
 from pydantic import AfterValidator
 from pydantic_core.core_schema import ValidationInfo
+from pydantic_forms.types import UUIDstr
 
 from gso.services import subscriptions
 
 T = TypeVar("T")
 
 
-def validate_field_is_unique(value: T, info: ValidationInfo) -> T:
+def validate_field_is_unique(subscription_id: UUIDstr, value: T, info: ValidationInfo) -> T:
     """Validate that a field is unique."""
-    if len(subscriptions.get_active_subscriptions_by_field_and_value(str(info.field_name), str(value))) > 0:
+    matched_subscriptions = subscriptions.get_active_subscriptions_by_field_and_value(str(info.field_name), str(value))
+    matched_subscriptions = list(
+        filter(lambda match: str(match.subscription_id) != subscription_id, matched_subscriptions)
+    )
+    if len(matched_subscriptions) > 0:
         msg = f"{info.field_name} must be unique"
         raise ValueError(msg)
     return value
 
 
-UniqueField = Annotated[T, AfterValidator(validate_field_is_unique)]
+UniqueField = Annotated[T, AfterValidator(partial(validate_field_is_unique, ""))]