chore: Update to the new version of brand-openedx in the new scope

[brian-smith-tcril]

Part of openedx/axim-engineering#23

This updates the @edx/brand alias to point to the brand-openedx package at
the openedx scope. This does not impact imports because this package is used
via an alias.

[openedx-webhooks]

Thanks for your pull request, but this repo does not accept outside contributions unless they are under contract. If you think this is an error, please contact @nedbat.