<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Work on this issue](https://contributors.gitlab.com/manage-issue?action=work&projectId=278964&issueIid=390941) - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=390941) </details> <!--IssueSummary end--> Create a GraphQL subscription called `mergeRequestStateUpdated` that will return a `MergeRequest` type which can include `state`. Triggering this subscription will be done separately.