Create test-case documents in latest subdir

We want to move to providing test cases for multiple generations of
Apertis so as to enable us to develop the bits we need to do this,
begin by putting the existing output in `latest/`.

Signed-off-by: Martyn Welch <martyn.welch@collabora.com>

.gitlab-ci.yml

@@ -27,7 +27,8 @@ test:
 pages:
   stage: deploy
   script:
-    - ./atc test-cases/ -d public/ --index-page
+    - mkdir public
+    - ./atc test-cases/ -d public/latest/ --index-page
   artifacts:
     paths:
       - public