Bump codemirror-graphql from 0.6.12 to 0.9.0 in /website (#6592)
Bumps [codemirror-graphql](https://github.com/graphql/graphiql) from 0.6.12 to 0.9.0.
- [Release notes](https://github.com/graphql/graphiql/releases)
- [Changelog](https://github.com/graphql/graphiql/blob/master/CHANGELOG.md)
- [Commits](https://github.com/graphql/graphiql/compare/v0.6.12...v0.9.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>