feat(swarm, libp2p): remove async-std

Pull-Request: #6074.

Author: jxs

.github/workflows/ci.yml

@@ -188,7 +188,6 @@ jobs:
       matrix:
         include:
           - features: "mdns tcp dns tokio"
-          - features: "mdns tcp dns async-std"
     steps:
       - uses: actions/checkout@v4