✅ improve mock client transport

Author: yanyongyu

tests/utils.py

@@ -8,4 +8,5 @@
 def get_mock_github(
     handle: Callable[[httpx.Request], httpx.Response],
 ) -> GitHub[UnauthAuthStrategy]:
-    return GitHub(transport=httpx.MockTransport(handle))
+    transport = httpx.MockTransport(handle)
+    return GitHub(transport=transport, async_transport=transport)