refactor: add default vars

roles/ynh_backup/tasks/backup.yml

@@ -20,7 +20,7 @@
 - name: Fail if variables are not used correctly
   ansible.builtin.fail:
     msg: You need to define variable ynh_backup.apps and / or ynh_backup.system to True
-  when: ynh_backup.apps | default(False) is false and ynh_backup.system | default(False) is false
+  when: ynh_backup.apps | default(True) is false and ynh_backup.system | default(True) is false
   tags: backup
 
 - name: Create backup folder if doesn't already exist

roles/ynh_backup/templates/ynh_backup.sh.j2

@@ -13,7 +13,7 @@ _fail() {
 
 _create_ynh_backup() {
   echo "Backing up $today YunoHost data now."
-  yunohost backup create {% if ynh_backup.system|default(ynh_backup.system == true) %}--system{% endif %}{% if ynh_backup.apps|default(ynh_backup.apps == true) %} --apps{% endif %}{% if ynh_backup.directory|default(ynh_backup.directory == "/data/backup") %} --output-directory {{ ynh_backup.directory }}/backup_"$today" {% endif %} || _fail "can't create a backup"
+  yunohost backup create {% if ynh_backup.system | default(True) %}--system{% endif %}{% if ynh_backup.apps | default(True) %} --apps{% endif %}{% if ynh_backup.directory | default("/data/backup") %} --output-directory {{ ynh_backup.directory }}/backup_"$today" {% endif %} || _fail "can't create a backup"
 
 }