minor fix

Author: BingqingLyu

.github/workflows/k8s-ci.yml

@@ -644,6 +644,8 @@ jobs:
         run: |
           . ~/.graphscope_env
           export RPC_TARGET=start_rpc_server_k8s
+          rustup toolchain install 1.81.0
+          rustup default 1.81.0
           cd interactive_engine/compiler && make build rpc.target=${RPC_TARGET}
           cd ${GITHUB_WORKSPACE}
           strip interactive_engine/executor/ir/target/release/${RPC_TARGET}