Throw warning and fail CI if CHANGELOG.md file has not been modified (

#1400)

* Reset head + add changelog workflow

* Make job fail

* Improve warning message

* update warning

.github/workflows/changelog.yml

@@ -0,0 +1,28 @@
+name: Changelog
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+
+jobs:
+  check-changelog:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@main
+        with:
+          fetch-depth: 0
+
+      - name: Check if CHANGELOG.md is modified
+        run: |
+          # Get the list of changed files in the PR
+          changed_files=$(git diff --name-only origin/${{ github.event.pull_request.base.ref }}...${{ github.sha }})
+
+          # Check if CHANGELOG.md is in the list of changed files
+          if echo "$changed_files" | grep -q '^CHANGELOG.md$'; then
+            echo "CHANGELOG.md has been modified."
+          else
+            echo $'::warning file=CHANGELOG.md::CHANGELOG.md has not been modified.\n This warning can be ignored if is has been explicitely decided not to log changes.\n Except in this situation, make sure to add log changes.'
+            exit 1
+          fi