Your requirements could not be resolved to an installable set of packages.
Problem 1
- The requested package satooshi/php-coveralls dev-master exists as satooshi/php-coveralls[0.1.0, 0.2.0, 0.3.0, 0.3.1, 0.3.2, 0.4.0, 0.5.0, 1.0.x-dev, 1.1.x-dev, 2.0.x-dev, v0.6.0, v0.6.1, v0.7.0, v0.7.1, v1.0.0, v1.0.1, v1.0.2, v1.1.0, v2.0.0] but these are rejected by your constraint.
This is a problem with composer install/update:
Greetings Jan