build(deps-dev): bump @octokit/graphql-schema from 15.18.0 to 15.21.0

Bumps [@octokit/graphql-schema](https://github.com/octokit/graphql-schema) from 15.18.0 to 15.21.0.
- [Release notes](https://github.com/octokit/graphql-schema/releases)
- [Commits](octokit/graphql-schema@v15.18.0...v15.21.0)

---
updated-dependencies:
- dependency-name: "@octokit/graphql-schema"
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

package.json

@@ -41,7 +41,7 @@
     "@graphql-codegen/typescript-document-nodes": "4.0.7",
     "@graphql-codegen/typescript-operations": "4.2.1",
     "@graphql-codegen/typescript-resolvers": "4.1.0",
-    "@octokit/graphql-schema": "15.18.0",
+    "@octokit/graphql-schema": "15.21.0",
     "@tsconfig/node20": "20.1.4",
     "@tsconfig/strictest": "2.0.5",
     "@types/gettext-parser": "4.0.4",