test: stabilize concurrency timing assertion

Author: Saitamasans

tests/integration/test_concurrency_locks.py

@@ -12,7 +12,7 @@
 
 class DelayedTransport(httpx.AsyncBaseTransport):
     async def handle_async_request(self, request: httpx.Request) -> httpx.Response:
-        await asyncio.sleep(0.1)
+        await asyncio.sleep(0.25)
         return httpx.Response(200, json={"ok": True}, request=request)
 
 
@@ -64,5 +64,4 @@ async def test_independent_workflows_run_concurrently_and_locks_serialize(tmp_pa
             make_document(True), env={"USER_ID": "u1"}
         )
         locked_elapsed = time.perf_counter() - start
-    assert concurrent_elapsed < 0.18
-    assert locked_elapsed >= 0.19
+    assert locked_elapsed - concurrent_elapsed >= 0.12