Hello,
Dirty solution without risk:
touch /etc/fail2ban/jail.d/piwigo.conf
touch /etc/fail2ban/filter.d/piwigo.conf
yunohost app upgrade -u https://github.com/YunoHost-Apps/piwigo_ynh piwigo --debug
Proper solution but riskier (you need to already have a backup of piwigo in case of problem!):
NO_BACKUP_UPGRADE=1 yunohost app upgrade -u https://github.com/YunoHost-Apps/piwigo_ynh piwigo --debug