wait for the first server to initialize DHT

.github/workflows/run-tests.yaml

@@ -72,6 +72,8 @@ jobs:
             --torch_dtype float32 --identity tests/test.id --host_maddrs /ip4/127.0.0.1/tcp/31337 --throughput 1 &
           SERVER1_PID=$!
           
+          sleep 5  # wait for the first server to initialize DHT
+          
           export INITIAL_PEERS=/ip4/127.0.0.1/tcp/31337/p2p/QmS9KwZptnVdB9FFV7uGgaTq4sEKBwcYeKZDfSpyKDUd1g
           # ^-- server 1 multiaddr is determined by --identity and --host_maddrs