If you absolutely need to trigger a handler every time then here are two options:
1) run a noop shell command which will always report as changed
- name: trigger nginx-restart
command: /bin/true
notify: nginx-restart
2) use debug along with changed_when: to trigger a handler
- debug: msg="trigger nginx-restart"
notify: nginx-restart
changed_when: true
Also of note for Option 1 and Check Mode: You may want to use check_mode: no
if using Ansible version 2.2 or higher or always_run: yes
if using earlier versions than that so that the task does not get skipped over in check mode. From my manual testing it looks like the handlers remain in check mode, but please be careful as your case may differ.