Modify the '.gitignore' file
Modify the '.gitignore' file

Since the horizon remove the 'run_tests.sh' file,
so there should remove '.venv' from the '.gitignore' file.

Change-Id: Iccddfef8e2733c0a2440ad940e6de674ec538b37

openstack/cloudkitty-dashboard,openstack/cloudkitty-dashboard,openstack/cloudkitty-dashboard,stackforge/cloudkitty-dashboard,stackforge/cloudkitty-dashboard,stackforge/cloudkitty-dashboard