[Skiboot] [PATCH] ci: Update github actions to run on Node 16

[Reza Arbab]

On Fri, Feb 10, 2023 at 10:52:01AM -0600, Reza Arbab wrote:
>Github is deprecating Node 12 for actions[1]. Support for Node 16 was
>added to github-pages-deploy-action in v4.4.1. Instead of specifying
>v4.2.5 in our workflow, only reference the major release, which will
>pick up the latest.

Applied to master.

-- 
Reza Arbab