Change twilio-run dependency version of serverless-runtime-types

I temporarily had to set the version of `@twilio-labs/serverless-runtime-types` to `2.1.0-rc.0` in order to avoid lerna to symlink the package inside `twilio-run`. After the deployment of `@twilio/runtime-handler@1.2.0` we should adjust it back to `2.1.0`. 