Check if requirements works instead of installing juypter book directly.

.gitlab-ci.yml

@@ -6,7 +6,7 @@ jupyter-build:
   stage: build
   image: python:3.10-slim
   script:
-    - pip install -U jupyter-book
+    - pip install -r requirements.txt
     - jupyter-book clean .
     - jupyter-book build .
   artifacts: