SNOW-756525 Add changelog check in CI (#1476)

Author: sfc-gh-stan

.github/workflows/changelog.yml

@@ -0,0 +1,20 @@
+name: Changelog Check
+
+on:
+  pull_request:
+    types: [opened, synchronize, labeled, unlabeled]
+    branches:
+      - main
+
+jobs:
+  check_change_log:
+    runs-on: ubuntu-latest
+    if: ${{!contains(github.event.pull_request.labels.*.name, 'NO-CHANGELOG-UPDATES')}}
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v3
+      with:
+        fetch-depth: 0
+
+    - name: Ensure DESCRIPTION.md is updated
+      run: git diff --name-only --diff-filter=ACMRT ${{ github.event.pull_request.base.sha }} ${{ github.sha }} | grep -wq "DESCRIPTION.md"