[SECURITY] Bump graphql from 2.3.16 to 2.3.21 (#936)

Bumps [graphql](https://github.com/rmosolgo/graphql-ruby) from 2.3.16 to 2.3.21.
- [Release notes](https://github.com/rmosolgo/graphql-ruby/releases)
- [Changelog](https://github.com/rmosolgo/graphql-ruby/blob/master/CHANGELOG.md)
- [Commits](rmosolgo/graphql-ruby@v2.3.16...v2.3.21)

---
updated-dependencies:
- dependency-name: graphql
  dependency-type: indirect
...

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

Author: dependabot[bot]

Gemfile.lock

@@ -181,7 +181,7 @@ GEM
     graphlient (0.8.0)
       faraday (~> 2.0)
       graphql-client
-    graphql (2.3.16)
+    graphql (2.3.21)
       base64
       fiber-storage
     graphql-client (0.23.0)