Daily update check message shows a <nil> when there is no message to show

[pskrbasu]

steampipe plugin install aws

<nil>
+------------------------------------------------------+
|                                                      |
| Introducing Powerpipe: Steampipe mods                |
| and dashboards are now separately available          |
| in Powerpipe (https://powerpipe.io/),                 |
| a new open-source project                            |
| (https://github.com/turbot/powerpipe).               |
|                                                      |
| The steampipe mod, check and dashboard commands will |
| be removed in a future version. Migration guide -    |
| https://powerpipe.io/blog/migrating-from-steampipe   |
|                                                      |
+------------------------------------------------------+


aws                            [====================================================================] Done

Installed plugin: aws@latest v0.133.0
Documentation:    https://hub.steampipe.io/plugins/turbot/aws