.travis.yml: disable Travis git --depth option
.travis.yml: disable Travis git --depth option

Travis by default clone with --depth=50. If the last tag is not within
this range (unlikely but possible), setuptools_scm can fail to derive
the version string.

greginvm/pyclipper,anthrotype/pyclipper,anthrotype/pyclipper,greginvm/pyclipper,greginvm/pyclipper,anthrotype/pyclipper