Repository owner is incorrectly identified for the simple theme

[GuySartorelli]

In https://github.com/silverstripe/silverstripe-simple/blob/3/.github/workflows/merge-up.yml we see this:
github.repository_owner == 'silverstripe-themes'
Should be github.repository_owner == 'silverstripe'

This is causing the merge-ups to not run for that repository. It's theoretically possible other repos are similarly incorrect.

[emteknetnz]

This will probably be resolved by #45

I've blocked this card on that issue and put this in awaiting to confirm later

[GuySartorelli]

This was fixed