[CI] Align apt-get commandline with other pages

.gitlab-ci.yml

@@ -7,7 +7,7 @@ variables:
 pages:
   stage: deploy
   before_script:
-  - apt update; apt install po4a -y
+  - apt-get -y update && apt-get -y install po4a
   - pip install -r requirements.txt
   script:
   - make publish; make publish