doc: ensure page creation date is correct.

.gitlab-ci.yml

@@ -142,6 +142,9 @@ preprocess-opensuse:
 pages:
   stage: deploy
   image: python
+  variables:
+    GIT_STRATEGY: clone
+    GIT_DEPTH: 0
   script:
     - pip install -r requirements.txt
     - mkdocs build --verbose --site-dir public