sources from git snapshot

raise depdendency on PHP 7.3
raise depdendency on phpunit/php-file-iterator 3
raise depdendency on phpunit/php-token-stream 4
raise depdendency on phpunit/php-text-template 2
raise depdendency on sebastian/code-unit-reverse-lookup 2
raise depdendency on sebastian/environment 5
raise depdendency on sebastian/version 3
rename to php-phpunit-php-code-coverage8
move to /usr/share/php/SebastianBergmann/CodeCoverage8