ci: add automatic build and deploy

.gitlab-ci.yml

+---
+
+stages:
+  - build
+  - deploy
+
+variables:
+  GIT_SUBMODULE_STRATEGY: recursive
+
+.global_tag: &global_tag_def
+  tags:
+    - latex
+
+# Compile latex presentation
+tex-compile:
+  <<: *global_tag_def
+  stage: build
+  image: aergus/latex
+  script:
+    # - git submodule init
+    # - git submodule update
+    - latexmk -pdf -f -interaction=nonstopmode *.tex
+  artifacts:
+    name: "$CI_PROJECT_NAME-$CI_COMMIT_SHA"
+    paths:
+      - "*.pdf"
+    expire_in: 12 hours
+  only:
+    - main
+    - dev
+
+# Expose pdf outputs publicly
+pages:
+  <<: *global_tag_def
+  stage: deploy
+  script:
+    - mkdir public
+    - cp *.pdf public
+  artifacts:
+    paths:
+      - public
+    expire_in: 12 hours
+  only:
+    - main
+
+
+# cache all auxilliary files to speed up compilation
+cache:
+  untracked: true
+  key: "$CI_BUILD_NAME"