base.py doesn't support workspaces with large number of users (no paging for users.list)

[renbeynolds]

When searching through users for the bot, the script errors saying unable to find bot name because the bot name is on the second page of results and the request does not take advantage of Slack's api pagination.

[ahelal]

@renbeynolds hey thank. are you able to submit a pr ?

[pvenum889]

When searching through users for the bot, the script errors saying "limit_required" because there are many users