Add bash to tox whitelist_externals
Add bash to tox whitelist_externals

Stop triggering triggering a “not installed in virtualenv” every time
bash is called. Since we use this in all tempest based jobs, we have
these unnecessary warnings all over the place.

Change-Id: I8af53c0241dbcd656c274944338384be0f2f250d

openstack/tempest,manasi24/tempest,masayukig/tempest,CiscoSystems/tempest,vedujoshi/tempest,flyingfish007/tempest,Vaidyanath/tempest,Juniper/tempest,manasi24/jiocloud-tempest-qatempest,CiscoSystems/tempest,afaheem88/tempest_neutron,varunarya10/tempest,LIS/lis-tempest,Lilywei123/tempest,cisco-openstack/tempest,danielmellado/tempest,vedujoshi/tempest,Juraci/tempest,tudorvio/tempest,zsoltdudas/lis-tempest,eggmaster/tempest,Tesora/tesora-tempest,pczerkas/tempest,ebagdasa/tempest,redhat-cip/tempest,rakeshmi/tempest,JioCloud/tempest,pandeyop/tempest,flyingfish007/tempest,hpcloud-mon/tempest,sebrandon1/tempest,afaheem88/tempest_neutron,tudorvio/tempest,yamt/tempest,danielmellado/tempest,FujitsuEnablingSoftwareTechnologyGmbH/tempest,cisco-openstack/tempest,bigswitch/tempest,pandeyop/tempest,Juraci/tempest,NexusIS/tempest,queria/my-tempest,openstack/tempest,Lilywei123/tempest,varunarya10/tempest,sebrandon1/tempest,afaheem88/tempest,JioCloud/tempest,xbezdick/tempest,neerja28/Tempest,LIS/lis-tempest,jaspreetw/tempest,rzarzynski/tempest,jamielennox/tempest,izadorozhna/tempest,ebagdasa/tempest,nunogt/tempest,tonyli71/tempest,hayderimran7/tempest,akash1808/tempest,alinbalutoiu/tempest,bigswitch/tempest,hayderimran7/tempest,tonyli71/tempest,Tesora/tesora-tempest,manasi24/jiocloud-tempest-qatempest,Juniper/tempest,izadorozhna/tempest,NexusIS/tempest,eggmaster/tempest,pczerkas/tempest,alinbalutoiu/tempest,dkalashnik/tempest,Vaidyanath/tempest,rakeshmi/tempest,redhat-cip/tempest,queria/my-tempest,neerja28/Tempest,afaheem88/tempest,jaspreetw/tempest,yamt/tempest,dkalashnik/tempest,akash1808/tempest,roopali8/tempest,roopali8/tempest,jamielennox/tempest,masayukig/tempest,manasi24/tempest,nunogt/tempest,xbezdick/tempest,zsoltdudas/lis-tempest,hpcloud-mon/tempest,rzarzynski/tempest,FujitsuEnablingSoftwareTechnologyGmbH/tempest