Adding user details to storybook publish script

[jonrohan]

The auto storybook script publishes and doesn't have a user attached to it, so we get commits that look like this:

primer/storybook@ef149d7

This pull adds user info so that @primer-css will be the committer.

@primer/design-systems

[shawnbot]

@jonrohan I queued this up for 10.7.1 in #527, but feel free to move it to #523 (10.8.0) if you'd like. Looks like we'll need to merge master into that branch to shrink the diff.

[shawnbot]

Looks good, let's ship this in v10.9.0!