* Send notifications to partecipants in issue comments

Closes #1216

Includes test (still failing)

* Do not include "labelers" to participants

Fix test to expect what GetParticipants return

* Add api url func.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

* fix: Add unit testing.

* fix: conflicts

* fix: remove trim

* fix: revert test function name.