Start caching dependencies

.gitlab-ci.yml

@@ -2,7 +2,15 @@ stages:
  - test
  - deploy
 
+cache:
+  paths:
+    - .apt
+
 before_script:
+  # Enable caching: https://gitlab.com/gitlab-org/gitlab-runner/-/issues/991#note_126864314
+  - rm -f /etc/apt/apt.conf.d/docker-clean
+  - mkdir .apt && mkdir /var/cache/apt/archives && mount --bind .apt /var/cache/apt/archives/
+
   - apt-get update --yes
   - apt-get install --yes build-essential cmake graphviz python3-pyqt5 xvfb xdg-utils lcov
   - python -m pip install --upgrade pip