PHPUnit made `\PHPUnit\TextUI\TestRunner` final

[spawnia]

Since PHPUnit made this class final, we should look for another way of hooking into its functionality.

I hacked together a quick fix for now by just copy-and-pasting the contents of the class, but there has to be a better way to achieve this.

[spawnia]

This should be resolved by #13.

Thank you @ecourtial for merging the fix and creating a new release. Would you mind creating another release with the proper semantic version number 1.0.0 (the current release is 1.0 and thus missing a segment).

[ecourtial]

@spawnia Done :)