Support September 2025 spec #447
Description
Parent issue for things that have changed in the September 2025 version of the spec and need adaption. To be done once we fully support any previous version.
https://github.com/graphql/graphql-spec/blob/main/changelogs/September2025.md
(Latest) As part of this we should go through all spec references in the code and documentation, and make sure they point to the latest supported version. Once we fully support any version of the spec, we should also document this explicitly.