Bump @octokit/graphql-schema in the octokit-dependencies group (#843)

Bumps the octokit-dependencies group with 1 update: [@octokit/graphql-schema](https://github.com/octokit/graphql-schema).


Updates `@octokit/graphql-schema` from 15.18.0 to 15.20.0
- [Release notes](https://github.com/octokit/graphql-schema/releases)
- [Commits](octokit/graphql-schema@v15.18.0...v15.20.0)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

package.json

@@ -26,7 +26,7 @@
     "@actions/core": "^1.10.1",
     "@actions/github": "^6.0.0",
     "@octokit/core": "^6.1.2",
-    "@octokit/graphql-schema": "^15.18.0",
+    "@octokit/graphql-schema": "^15.20.0",
     "@octokit/plugin-paginate-graphql": "^5.2.2",
     "ansi-styles": "^6.2.1",
     "temporal-polyfill": "^0.2.5",