Improve release workflow by upgrading package versions in test app

Summary

During the ui kit release, we also trigger a release on the design system by upgrading the version of our packages to the latest version that was just released. We should do the same for the test app too as that's fallen quite far behind.

💬 Description

We should duplicate the design system repo trigger and set off a workflow in the test app repo.

The team doesn't regularly check that repo like we do with the ui kit and design system, so instead of it triggering a PR in the test repo like the check versions workflow on the design system, maybe there's a way we can just automatically push the changes. Or if there was a way it could just require one reviewer and we could add it to our release guidance to make sure whoever does the release is responsible for merging that PR.

Why do we need it?

We should use our test app a lot more often for debugging user issues and we'll be more likely to if it's up to date.

Start with .github/workflows/ic-ui-kit-release-merged.yml, especially the design system repo trigger, and compare it with the check-versions workflow in the design system repository. Review how the test app repository receives package updates and determine whether the release should push changes or create a reviewable PR. Done means the test app's package versions are updated automatically after a UI kit release.