Add `@sentry/browser` to renovate
### Problem
We want to upgrade the `@sentry/browser` package to `6.10.0` or higher.
This could either be really simple, or very painful.
We should do this by adding the package to [renovate](https://gitlab.com/gitlab-org/frontend/renovate-gitlab-bot).
### Things to consider
- [x] We need to be very careful that this upgrade doesn't break our current processes
- [x] We need to be careful this upgrade works with our self-hosted version of sentry
- [x] We should make ~"group::foundations" aware of this change (cc @mikegreiling)
issue