Update to api-platform 2.7.0
- Some interfaces we use are no longer there (we could report this? were they officially documented?)
- There is a compat mode which is enabled by default. When do we switch it off? At the earliest when we have ported all bundles.
- Do we support 2.6 and 2.7 at the same time? Likely tricky...
- How do we document the update for users?
- Do we bump minor?