chore(deps): bump graphql-relational-schema-transformer

Bumps [graphql-relational-schema-transformer](https://github.com/aws-amplify/amplify-category-api/tree/HEAD/packages/graphql-relational-schema-transformer) from 2.18.6 to 2.21.26.
- [Release notes](https://github.com/aws-amplify/amplify-category-api/releases)
- [Changelog](https://github.com/aws-amplify/amplify-category-api/blob/main/packages/graphql-relational-schema-transformer/CHANGELOG.md)
- [Commits](https://github.com/aws-amplify/amplify-category-api/commits/[email protected]/packages/graphql-relational-schema-transformer)

---
updated-dependencies:
- dependency-name: graphql-relational-schema-transformer
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>