Remove iso8601 and anyjson from requirements.txt
Remove iso8601 and anyjson from requirements.txt

It looks like they are not used.

Change-Id: I4865e8478932c1a881eb34165cdce9addd737ec8

bigswitch/tempest,Juniper/tempest,sebrandon1/tempest,openstack/tempest,vedujoshi/tempest,masayukig/tempest,vedujoshi/tempest,Tesora/tesora-tempest,openstack/tempest,masayukig/tempest,Tesora/tesora-tempest,sebrandon1/tempest,cisco-openstack/tempest,bigswitch/tempest,Juniper/tempest,cisco-openstack/tempest