BotmanStudio v2 に slack driver をインストールする

2018/06/04現在、 botman/botman 2.0 に slack driver を追加すると依存関係でエラーになってしまう。

$ php artisan botman:install-driver slack
Installing driver "Slack"
Using version ^2.1 for botman/driver-slack

./composer.json has been updated

Loading composer repositories with package information

Updating dependencies (including require-dev)

Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Conclusion: don't install botman/driver-slack 2.1.3
    - Conclusion: don't install botman/driver-slack 2.1.2
    - Conclusion: don't install botman/driver-slack 2.1.1
    - Installation request for botman/driver-slack ^2.1 -> satisfiable by botman/driver-slack[2.1.0, 2.1.1, 2.1.2, 2.1.3].
    - Conclusion: don't install react/event-loop v0.5.2
    - botman/driver-slack 2.1.0 requires mpociot/slack-client ~1.0 -> satisfiable by mpociot/slack-client[1.0].
    - mpociot/slack-client 1.0 requires react/event-loop ^0.4.1 -> satisfiable by react/event-loop[v0.4.1, v0.4.2, v0.4.3].
    - mpociot/slack-client 1.0 requires react/event-loop ^0.4.1 -> satisfiable by react/event-loop[v0.4.1, v0.4.2, v0.4.3].
    - Can only install one of: react/event-loop[v0.4.1, v0.5.2].
    - Can only install one of: react/event-loop[v0.4.2, v0.5.2].
    - Can only install one of: react/event-loop[v0.4.3, v0.5.2].
    - Can only install one of: react/event-loop[v0.5.2, v0.4.1].
    - Installation request for react/event-loop (locked at v0.5.2) -> satisfiable by react/event-loop[v0.5.2].



Installation failed, reverting ./composer.json to its original content.

Error installing driver "Slack"

composer.json に定義されている react/event-loop のバージョンを下げてやるとインストールすることができた。

    "require": {
        "php": ">=7.1.3",
        "botman/botman": "~2.0",
        "botman/driver-slack": "2.0",
        "botman/driver-web": "~1.0",
        "botman/studio-addons": "~1.2.1",
        "botman/tinker": "~1.0",
        "fideloper/proxy": "~4.0",
        "laravel/framework": "5.6.*",
        "laravel/tinker": "~1.0",
        "react/event-loop": "v0.4.1"
    },