Map current oncall shift to a Slack usergroup.
PAGERDUTY_TOKEN
: a read-only token for PagerDutyPAGERDUTY_SCHEDULE_ID
: the ID of the schedule to querySLACK_BOT_TOKEN
: a bot token from a Slack app, permissions necessary:users:read.email
andusergroups:write
SLACK_USERGROUP_ID
: the id of the usergroup in Slack