fix(mypy): cast legacy approval task_id after None-check

backend/app/services/approval_task_links.py

@@ -3,7 +3,7 @@
 from __future__ import annotations
 
 from collections.abc import Iterable, Sequence
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, cast
 from uuid import UUID
 
 from sqlalchemy import case, delete, exists, func
@@ -266,8 +266,9 @@ async def task_counts_for_board(
     for legacy_task_id, total, pending in list(await session.exec(legacy_statement)):
         if legacy_task_id is None:
             continue
-        previous = counts.get(legacy_task_id, (0, 0))
-        counts[legacy_task_id] = (
+        task_uuid = cast(UUID, legacy_task_id)
+        previous = counts.get(task_uuid, (0, 0))
+        counts[task_uuid] = (
             previous[0] + int(total or 0),
             previous[1] + int(pending or 0),
         )