roles: strict truthy values

According to Ansible we can use yes, true, True, "or any quoted st-
ring" for a boolean true, but ansible-lint wants us to use either
true or false.

See: https://chronicler.tech/red-hat-ansible-yes-no-and/

roles/nginx/tasks/letsencrypt.yml

@@ -79,8 +79,8 @@
     ansible.builtin.systemd:
       name: renew-letsencrypt.timer
       state: started
-      enabled: yes
-      daemon_reload: yes
+      enabled: true
+      daemon_reload: true
 
   when: (ansible_distribution == 'Ubuntu' and ansible_distribution_version is version('20.04', '=='))
         or (ansible_distribution == 'Debian' and ansible_distribution_version is version('11', '=='))