dev-python/pycups: version bump, enable python-3.6

dev-python/pycups: version bump, enable python-3.6

The package build with python 3.6

 * Package:    dev-python/pycups-1.9.73-r1
 * Repository: vivovl
 * Maintainer: reavertm@gentoo.org printing@gentoo.org
 * USE:        abi_x86_64 amd64 elibc_glibc kernel_linux python_targets_python2_7 python_targets_python3_6 userland_GNU
 * FEATURES:   compressdebug preserve-libs sandbox splitdebug test userpriv usersandbox

ebuild has no tests, "app-admin/system-config-printer", the only user on this system work fine