dist/ubuntu/dep: Drop python-support on Ubuntu 16.04
dist/ubuntu/dep: Drop python-support on Ubuntu 16.04

Ubuntu 16.04 seems dropped python-support, so remove it from thrift package.

Signed-off-by: Takuya ASADA <4ebfb6f510af412d6e89fefa3ab96d9c8b5e3fff@scylladb.com>

scylladb/scylla,raphaelsc/scylla,avikivity/scylla,kjniemi/scylla,duarten/scylla,raphaelsc/scylla,scylladb/scylla,scylladb/scylla,duarten/scylla,avikivity/scylla,scylladb/scylla,duarten/scylla,kjniemi/scylla,avikivity/scylla,kjniemi/scylla,raphaelsc/scylla