chore(test): pin asyncio_default_fixture_loop_scope to function

pytest.ini

@@ -1,2 +1,11 @@
 [pytest]
 asyncio_mode = auto
+# pytest-asyncio 1.x changed the default fixture loop scope. With it
+# unset, pytest-asyncio 1.x emits a deprecation warning and the
+# session-scoped fixtures bind to a different event loop than the
+# per-test functions, producing "another operation is in progress"
+# (asyncpg) and "attached to a different loop" (asyncio) errors.
+# Pinning the scope explicitly keeps pytest-asyncio 0.24.x and 1.x
+# behaviorally identical and unblocks the Dependabot pytest-asyncio
+# 1.3.0 bump (#40).
+asyncio_default_fixture_loop_scope = function