gRPC SAN whitelist breaks with empty list

gRPC SAN whitelist breaks with empty list: a task in MiMo-V2.6-RL-oss: Agentic RL Environments (MiMo RL release). grpc/creds:serverTransportCredentials.validateClient is meant to ignore the check if the acceptedSANs map it is constructed with is nil. This never happens as the map is constructed…