Merge pull request #4 from sorabito/feature/AS-12010

AS-12010 added new files api methods and moved old api methods to api-files-deprecated

Merge pull request #3 from sorabito/feature/pharo12-support

Feature/pharo12 support

Merge pull request #2 from sorabito/feature/files_upload

fix files.upload api

Merge pull request #1 from sorabito/feature/post_by_json

Conforming to the new API, PSlackClient>>post:withValues: now simply posts a json document

update for Pharo7.0

api support added

- chat.delete
- im.list
- users.list

initial