Composer And Travis Updates

What I know for sure is that if you specify `z` part of `~x.y.z` then only versions where `x.y` matches exactly will be used.

You specify only `~x.y` part then versions where `x.` matches will be used.

For more info you can read here: https://getcomposer.org/doc/01-basic-usage.md#next-significant-release-tilde-operator-

Yes, according to `~0.8` the `0.9` is the Mockery version that will be used, but why not specifying `~0.9` right away since you know which latest released version is at the moment.