Remove unused imports
Remove unused imports

Remove unused imports in tools/install_venv.py

Change-Id: Ia2fbb4ece5c8bcdee96503f0f853f826ae4f3dfa
Closes-Bug: #1265267

openstack/networking-mlnx,moshele/networking-mlnx-master,openstack/networking-mlnx,stackforge/networking-mlnx,stackforge/networking-mlnx,moshele/networking-mlnx