According to recent conversation from the PR #337 and @keradus opinion

I believe we can drop <7.2 by now
also, one could upload the coverage with php-coveralls v2.5.3. they will not receive any new versions of php-coveralls, but also not that much is changing in this project and they don't need to run cutting-edge version of php-coveralls, and running legacy PHP version could be bigger problem to start with ;)