Slack-Node use deprecated attributes when posting messages.

[trygvis]

Describe the bug

The as_user flag for the "post message" request is deprecated and can't be included if the user is using bot tokens. If it is included this is returned from Slack:

ok	error	deprecated_argument
false	invalid_arguments	as_user

https://api.slack.com/methods/chat.postMessage#arg_as_user

To Reproduce

Try to send a message with Authentication=Access Token and use a Bot token.

Environment (please complete the following information):

• n8n Version HEAD form master.

Additional context

If I add delete body.as_user at line 456 of Slack.node.ts the message is posted as my bot user.

A proper fix I think would be to remove the as_user entirely.

[RicardoE105]

Hey, @trygvis thanks for putting that together. I will check and keep you updated.

[RicardoE105]

@trygvis Just sent a PR fixing this, will let you know when is released. Again, Thanks.

[janober]

Fix got released with n8n@0.71.0

[inn0kenty]

The as_user parameter may not be used with newer bot tokens. But still, it may be used with user tokens. This fix broken this possibility.

The as_user with user token works fine in 0.70.0.

So, I suppose we should delete as_user from a request body only when it false. In this case, bot tokens and as_user with user tokens will be work.