Travis tests on php 7.3. fail

[Joachim Fritschi]

Have no idea why every php version works except 7.2

[Sjoerd Wenker]

For some reason the image for PHP 7.3 installs Xdebug 3 instead of Xdebug 2.

[Joachim Fritschi]

Thanks, good catch. That at least gives us some idea where to search...

[Joachim Fritschi]

All Travis tests are now okay