Update REST API Version
Update REST API Version

According to this file: https://raw.githubusercontent.com/Azure/azure-sdk-for-node/master/lib/services/keyVault/lib/keyVaultClient.js

The latest version supports 7.0
Azure/azure-sdk-for-node,Azure/azure-sdk-for-node,xingwu1/azure-sdk-for-node,Azure/azure-sdk-for-node,xingwu1/azure-sdk-for-node,xingwu1/azure-sdk-for-node