[ci] first try

.gitlab-ci.yml

+image: mpoquet/latex-minimal_ci:latest
+
+variables:
+  GIT_SUBMODULE_STRATEGY: normal
+
+stages:
+  - build
+
+slides:
+  stage: build
+  script:
+    - nix-build
+    - cp -rL --no-preserve=all result/slides.pdf ./
+  artifacts:
+    paths:
+      - slides.pdf