Authentication doesn't work

[jumarko]

It seems that the auth style used by the library, namely passing token in query params no longer works:

{:error "invalid_auth", :response {:ok false, :error "invalid_auth"}}

You need to pass the token in the Authorization header.
Afaik, the easiest way to do this is to use the :oauth-token param accepted by clj-http.
Here's what I ended up using: curiousprogrammer-net/slack-pom@f998e92#diff-1a6ed93c553296dc723c8009dc2fd60183c5a3c00d4b50b6ca511fbdead178ccR20