there is an error with phpmyadmin since few weeks.
To install phpmyadmin properly, after using ee to create the folder, install composer :
curl -sS https://getcomposer.org/installer | php
mv composer.phar /usr/bin/composer
Then login as www-data :
su - www-data
and go into the phpmyadmin folder
finally run :
It will update phpmyadmin dependencies and fix the issue.