Fix: use subquery() in count_matching_* accessors

Fixes a SQLAlchemy deprecation warning.

src/aleph/db/accessors/posts.py

@@ -315,10 +315,10 @@ def count_matching_posts(
             pagination=0,
             start_date=start_date,
             end_date=end_date,
-        )
+        ).subquery()
     else:
         # Without filters, counting the number of original posts is faster.
-        select_stmt = select(PostDb).where(PostDb.amends.is_(None))
+        select_stmt = select(PostDb).where(PostDb.amends.is_(None)).subquery()
 
     select_count_stmt = select(func.count()).select_from(select_stmt)
     return session.execute(select_count_stmt).scalar_one()

tests/api/test_list_messages.py

@@ -67,8 +67,7 @@ async def test_get_messages(fixture_messages: Sequence[Dict[str, Any]], ccn_api_
 async def test_get_messages_filter_by_channel(fixture_messages, ccn_api_client):
     async def fetch_messages_by_channel(channel: str) -> Dict:
         response = await ccn_api_client.get(MESSAGES_URI, params={"channels": channel})
-        text = await response.text()
-        assert response.status == 200, text
+        assert response.status == 200, await response.text()
         return await response.json()
 
     data = await fetch_messages_by_channel("unit-tests")