ci: add prepare_release stage to generate CHANGELOG.md for release

.gitlab-ci.yml

@@ -2,9 +2,26 @@ include:
 - template: 'Workflows/MergeRequest-Pipelines.gitlab-ci.yml'
 
 stages:
+- prepare
 - build
 
 build:
   stage: build
   script:
   - env | sort
+
+prepare_release:
+  stage: prepare
+  image:
+    name: orhunp/git-cliff:latest
+    entrypoint: [ "" ]
+  variables:
+    GIT_STRATEGY: clone # clone entire repo instead of reusing workspace
+    GIT_DEPTH: 0 # avoid shallow clone to give cliff all the info it needs
+  script:
+  - git-cliff --current > CHANGELOG.md
+  artifacts:
+    paths:
+    - CHANGELOG.md
+  rules:
+  - if: $CI_DEFAULT_BRANCH == $CI_COMMIT_BRANCH