aggiorna la versione del compositore
composer self-update
comando auto aggiornamento compositore
composer self-update
php compositore aggiornamento
php composer.phar update
aggiorna la versione php del compositore
php7.3 -f /usr/local/bin/composer update
aggiorna compositore
To update composer command just find location of composer.phar and update as:
where composer #Retrieves you location of your composer.phar
cd path_to_composer.phar #Move to directory with composer.phar
php composer.phar self-update #Update your composer