Webhook merge_request missing reviewer field

Summary

The webhook payload for merge requests is missing the reviewer field.

Steps to reproduce

Fire a "merge request" webhook.

What is the current bug behavior?

The object_attributes object is missing the reviewer field.

What is the expected correct behavior?

The object_attributes object shows the corresponding action in the reviewer field.

Relevant logs and/or screenshots

{
  "object_kind": "merge_request",
  "event_type": "merge_request",
  "user": {
    "id": 89,
    "name": "Эрл Капаров",
    "username": "Erl",
    "avatar_url": "https://code.groupstp.ru/uploads/-/system/user/avatar/89/avatar.png",
    "email": "e.kaparov@groupstp.ru"
  },
  "project": {
    "id": 95,
    "name": "Test Proj for Telegram Bot",
    "description": "",
    "web_url": "https://code.groupstp.ru/Erl/test-proj-for-telegram-bot",
    "avatar_url": null,
    "git_ssh_url": "git@code.groupstp.ru:Erl/test-proj-for-telegram-bot.git",
    "git_http_url": "https://code.groupstp.ru/Erl/test-proj-for-telegram-bot.git",
    "namespace": "Эрл Капаров",
    "visibility_level": 20,
    "path_with_namespace": "Erl/test-proj-for-telegram-bot",
    "default_branch": "main",
    "ci_config_path": "",
    "homepage": "https://code.groupstp.ru/Erl/test-proj-for-telegram-bot",
    "url": "git@code.groupstp.ru:Erl/test-proj-for-telegram-bot.git",
    "ssh_url": "git@code.groupstp.ru:Erl/test-proj-for-telegram-bot.git",
    "http_url": "https://code.groupstp.ru/Erl/test-proj-for-telegram-bot.git"
  },
  "object_attributes": {
    "assignee_id": null,
    "author_id": 89,
    "created_at": "2021-08-18 13:52:10 UTC",
    "description": "",
    "head_pipeline_id": null,
    "id": 2942,
    "iid": 5,
    "last_edited_at": null,
    "last_edited_by_id": null,
    "merge_commit_sha": null,
    "merge_error": null,
    "merge_params": {
      "force_remove_source_branch": "1"
    },
    "merge_status": "cannot_be_merged",
    "merge_user_id": null,
    "merge_when_pipeline_succeeds": false,
    "milestone_id": null,
    "source_branch": "newe",
    "source_project_id": 95,
    "state_id": 1,
    "target_branch": "main",
    "target_project_id": 95,
    "time_estimate": 0,
    "title": "Newe2",
    "updated_at": "2021-08-18 13:58:15 UTC",
    "updated_by_id": 89,
    "url": "https://code.groupstp.ru/Erl/test-proj-for-telegram-bot/-/merge_requests/5",
    "source": {
      "id": 95,
      "name": "Test Proj for Telegram Bot",
      "description": "",
      "web_url": "https://code.groupstp.ru/Erl/test-proj-for-telegram-bot",
      "avatar_url": null,
      "git_ssh_url": "git@code.groupstp.ru:Erl/test-proj-for-telegram-bot.git",
      "git_http_url": "https://code.groupstp.ru/Erl/test-proj-for-telegram-bot.git",
      "namespace": "Эрл Капаров",
      "visibility_level": 20,
      "path_with_namespace": "Erl/test-proj-for-telegram-bot",
      "default_branch": "main",
      "ci_config_path": "",
      "homepage": "https://code.groupstp.ru/Erl/test-proj-for-telegram-bot",
      "url": "git@code.groupstp.ru:Erl/test-proj-for-telegram-bot.git",
      "ssh_url": "git@code.groupstp.ru:Erl/test-proj-for-telegram-bot.git",
      "http_url": "https://code.groupstp.ru/Erl/test-proj-for-telegram-bot.git"
    },
    "target": {
      "id": 95,
      "name": "Test Proj for Telegram Bot",
      "description": "",
      "web_url": "https://code.groupstp.ru/Erl/test-proj-for-telegram-bot",
      "avatar_url": null,
      "git_ssh_url": "git@code.groupstp.ru:Erl/test-proj-for-telegram-bot.git",
      "git_http_url": "https://code.groupstp.ru/Erl/test-proj-for-telegram-bot.git",
      "namespace": "Эрл Капаров",
      "visibility_level": 20,
      "path_with_namespace": "Erl/test-proj-for-telegram-bot",
      "default_branch": "main",
      "ci_config_path": "",
      "homepage": "https://code.groupstp.ru/Erl/test-proj-for-telegram-bot",
      "url": "git@code.groupstp.ru:Erl/test-proj-for-telegram-bot.git",
      "ssh_url": "git@code.groupstp.ru:Erl/test-proj-for-telegram-bot.git",
      "http_url": "https://code.groupstp.ru/Erl/test-proj-for-telegram-bot.git"
    },
    "last_commit": {
      "id": "3d28c632e83898b6534f9b6d9f241fee2648e72d",
      "message": "Обновить .gitignore",
      "title": "Обновить .gitignore",
      "timestamp": "2021-08-11T12:53:43+00:00",
      "url": "https://code.groupstp.ru/Erl/test-proj-for-telegram-bot/-/commit/3d28c632e83898b6534f9b6d9f241fee2648e72d",
      "author": {
        "name": "Эрл Капаров",
        "email": "e.kaparov@groupstp.ru"
      }
    },
    "work_in_progress": false,
    "total_time_spent": 0,
    "time_change": 0,
    "human_total_time_spent": null,
    "human_time_change": null,
    "human_time_estimate": null,
    "assignee_ids": [],
    "state": "opened",
    "action": "update"
  },
  "labels": [],
  "changes": {
    "updated_at": {
      "previous": "2021-08-18 13:52:10 UTC",
      "current": "2021-08-18 13:58:15 UTC"
    },
    "updated_by_id": {
      "previous": null,
      "current": 89
    }
  },
  "repository": {
    "name": "Test Proj for Telegram Bot",
    "url": "git@code.groupstp.ru:Erl/test-proj-for-telegram-bot.git",
    "description": "",
    "homepage": "https://code.groupstp.ru/Erl/test-proj-for-telegram-bot"
  }
}