tests: allow application/x-cd-image as content type for ISO files
Some openSUSE mirrors return application/x-cd-image
as content type for
ISO files. As it is the canonical MIME type name of ISO files in
shared-mime-info (the freedesktop.org database), add it to the allowed
list of content types for ISO files.
Signed-off-by: Pino Toscano ptoscano@redhat.com