Update nodejs version to 16

[duddu]

This PR updates the nodejs matrix version to 16.
As recommended by GitHub with the following warning:

Node.js 12 actions are deprecated. For more information see: https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/. Please update the following actions to use Node.js 16: shimataro/ssh-key-action

Solves #207

[davereid-pfg]

https://github.com/shimataro/ssh-key-action/blob/develop/action.yml#L29 needs to be updated as well, this is not the only change needed.

[duddu]

thanks @davereid-pfg, updated.

@shimataro when you got time to have a glance, ping if there's anything missing/in need for update, ta!

[shimataro]

Very sorry for late response, and thank you for your request!

Since CI fails to read secret environment variables, I merge it into my branch.
After checking, it will be merged into develop!