Add GitLab CI configuration

.gitignore

@@ -1 +1,2 @@
 /_build/
+/public/

.gitlab-ci.yml

@@ -0,0 +1,15 @@
+image: registry.gitlab.com/paddy-hack/sphinx/debian/pdf:2.2.1
+
+pages:
+  before_script:
+    - apt-get update  -qq
+    - apt-get install -qqy --no-install-recommends
+              python3-setuptools
+              python3-wheel
+              git
+    - pip3 --quiet install -r requirements.txt
+  script:
+    - sphinx-versioning build -P sane-standard.pdf ./ public/
+  artifacts:
+    paths:
+      - public