Bump graphql from 2.5.19 to 2.5.21

Bumps [graphql](https://github.com/rmosolgo/graphql-ruby) from 2.5.19 to 2.5.21.
- [Release notes](https://github.com/rmosolgo/graphql-ruby/releases)
- [Changelog](https://github.com/rmosolgo/graphql-ruby/blob/master/CHANGELOG.md)
- [Commits](rmosolgo/graphql-ruby@v2.5.19...v2.5.21)

---
updated-dependencies:
- dependency-name: graphql
  dependency-version: 2.5.21
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

Gemfile.lock

@@ -220,7 +220,7 @@ GEM
       thor (>= 1.0.0)
     graphiql-rails (1.10.5)
       railties
-    graphql (2.5.19)
+    graphql (2.5.21)
       base64
       fiber-storage
       logger