Authentication does not work with new Apps

[simonfagerholm]

The way PSSlack send the token to slack is no longer supported on newly created apps:
https://api.slack.com/changelog/2020-11-no-more-tokens-in-querystrings-for-newly-created-apps=0

I have confirmed this with slack support.

The Invoke-RestMethod call should either be changed to use arguments -Method POST (confirmed to work) or the token should be included in an authorization header: Header = @{ Authorization = "Bearer $Token" } (also confirmed to word).

Both ways should be backwards compatible according to documentation

[simonfagerholm]

I created a PR for the slack recommended header method

[mhudson]

Patch confirmed working. Thanks @simonfagerholm 👍

[tstooke]

Hello wonderful people! I was wondering if this PR made it to being published in PSGallery? Looks like version 1.0.6 out there still has the older token handling? This package is awesome and just what we need to simplify our Slack integration, but we really need it to work with newer Slack Apps.

[marcinpolanski]

same here, authentication for me does not work on a newly created app.

[nascentt]

Any reason why Simon's fixes haven't been merged to master?

After wasting time trying to get psslack working I found Simon's fork which works perfectly.

[simonfagerholm]

@nascentt Post in the PR to get the attention of the repo owner 👍