Fix bot trigger event
Fix bot trigger event

Issue events don't contain a 'comment' entry:
https://developer.github.com/v3/issues/events/#response-2

Issue comments also contain the original issue body:
https://developer.github.com/v3/activity/events/types/#issuecommentevent

That's why it was triggering even for comments on the issue.

Also changed to startsWith because there's no need to support
the command anywhere in the body IMO.

Fix #6895

Akasurde/pytest,The-Compiler/pytest,nicoddemus/pytest,pytest-dev/pytest,The-Compiler/pytest,RonnyPfannschmidt/pytest,alfredodeza/pytest,nicoddemus/pytest,markshao/pytest