graphql 17

### Feature description

As far as I see postgraphile is currently built on/for GraphQL v16. As GraphQL v17 is released and I haven't found a tracking issue for support yet, I'm adding this.

### Motivating example

Not urgent for me, just thinking about the future of the ecosystem.

### Breaking changes

tbd

### Supporting development

I [tick all that apply]:

- [ ] am interested in building this feature myself
- [ ] am interested in collaborating on building this feature
- [x] am willing to help testing this feature before it's released
- [ ] am willing to write a test-driven test suite for this feature (before it exists)
- [ ] am a [Graphile sponsor](https://www.graphile.org/sponsor/) ❤️
- [ ] have an active [support or consultancy contract](https://www.graphile.org/support/) with Graphile

This issue is a future-looking request to track GraphQL 17 support in the PostGraphile ecosystem, but it names no files, tests, or entry points. Begin by identifying the repository's GraphQL 16 integration and compatibility tests; done would require an agreed scope and verified GraphQL 17 support.

Written by the indexing model from the issue text.