Update `chat_update` method not to raise error with parameter which contains only `reply_broadcast`

[colorbox]

chat.update API accepts request which contain only one optional parameter reply_broadcast. This PR update guard part of chat_update method to accept parameter which contains only reply_broadcast.

refs) https://api.slack.com/methods/chat.update

[colorbox]

Sorry, This PS is not proper to this repository.

[colorbox]

I misunderstand about chat.1.patch file and slack-api-ref repository. Do I have to update chat.1.patch?

[dblock]

Yeah, this file is auto-generated via lib/tasks/web.rake, so any additional changes need to be patched. I would start by updating https://github.com/slack-ruby/slack-api-ref (I think its cron that gets the Slack API docs may be dead), then update that here and re-generate the API, and only then see if it needs a patch. See https://github.com/slack-ruby/slack-ruby-client/blob/master/CONTRIBUTING.md#update-slack-web-api for details.

[dblock]

1 Error 🚫 One of the lines below found in CHANGELOG.md doesn't match the expected format. Please make it look like the other lines, pay attention to version numbers, periods, spaces and date formats.

* [#404](https://github.com/slack-ruby/slack-ruby-client/pull/404): Update `chat_update` method not to raise error with parameter which contains only `reply_broadcast`- [@colorbox](https://github.com/colorbox).

Generated by 🚫 Danger

You also have to fix this ^, the problem here is a missing space before -.

[dblock]

Thanks, merged!

[colorbox]

❤️