The requirement on nette/php-generator is ^2.6.1 || ~3.0.0. This means that composer will install the 3.0.5 release (highest release matching that range), while the latest release is 3.2.0.
Is this an expected change ? And is 3.0.x still maintained ? If no, the constraint should be changed either to force using a maintained 2.x version or to allow newer 3.x version.