update env template output
update env template output

When update with unexisting env template, the output contain '&lt;'
and '&gt;'.

murano env-template-update 849c781b2ef84a6a8961b520c11f7322 test
404 Not Found: EnvTemplate &lt;TempId 849c781b2ef84a6a8961b520c11f7322&gt;
is not found (HTTP 404)

Change-Id: Ifcbdc4cb5846de35e55fbeeaf21f9ce3d4748e36

openstack/python-muranoclient,openstack/python-muranoclient