Debian default back to PHP 5 to use Debian's default repository rather than the 3rd party repo. To get Debian 7 now go to debian/resources/config.php and change it to 7.
@@ -15,4 +15,4 @@ database_repo=official # PostgresSQL official, system, 2ndquadrant
database_backup=false # true or false
# General Settings
-php_version=7 # PHP version 5 or 7
+php_version=5 # PHP version 5 or 7