Add check-release-notes CI job (#5)

Also add a release notes file and a template release notes file.

Author: shsms

.github/RELEASE_NOTES.template.md

@@ -0,0 +1,17 @@
+# Frequenz Component Graph Release Notes
+
+## Summary
+
+<!-- Here goes a general summary of what this release is about -->
+
+## Upgrading
+
+<!-- Here goes notes on how to upgrade from previous versions, including deprecations and what they should be replaced with -->
+
+## New Features
+
+<!-- Here goes the main new features and examples or instructions on how to use them -->
+
+## Bug Fixes
+
+<!-- Here goes notable bug fixes that are worth a special mention or explanation -->

.github/workflows/ci.yaml

@@ -1,8 +1,14 @@
 name: Component Graph CI
 
 on:
+  merge_group:
   push:
-    branches: [ v0.x.x ]
+    branches-ignore:
+      # Ignore pushes to merge queues.
+      # We only want to test the merge commit (`merge_group` event), the hashes
+      # in the push were already tested by the PR checks
+      - 'gh-readonly-queue/**'
+      - 'dependabot/**'
   pull_request:
 
 jobs:

.github/workflows/dco-merge-queue.yml

@@ -0,0 +1,11 @@
+# Based on https://github.com/hyperledger/besu/pull/5207/files
+name: DCO
+on:
+  merge_group:
+
+jobs:
+  DCO:
+    runs-on: ubuntu-latest
+    if: ${{ github.actor != 'dependabot[bot]' }}
+    steps:
+      - run: echo "This DCO job runs on merge_queue event and doesn't check PR contents"

.github/workflows/release-notes-check.yml

@@ -0,0 +1,30 @@
+name: Release Notes Check
+
+on:
+  merge_group:
+  pull_request:
+    types:
+      # On by default if you specify no types.
+      - "opened"
+      - "reopened"
+      - "synchronize"
+      # For `skip-label` only.
+      - "labeled"
+      - "unlabeled"
+
+
+jobs:
+  check-release-notes:
+    name: Check release notes are updated
+    runs-on: ubuntu-latest
+    permissions:
+      pull-requests: read
+    steps:
+      - name: Check for a release notes update
+        if: github.event_name == 'pull_request'
+        uses: brettcannon/check-for-changed-files@871d7b8b5917a4f6f06662e2262e8ffc51dff6d1 # v1.2.1
+        with:
+          file-pattern: "RELEASE_NOTES.md"
+          prereq-pattern: "src/**"
+          skip-label: "cmd:skip-release-notes"
+          failure-message: "Missing a release notes update. Please add one or apply the ${skip-label} label to the pull request"

RELEASE_NOTES.md

@@ -0,0 +1,17 @@
+# Frequenz Component Graph Release Notes
+
+## Summary
+
+<!-- Here goes a general summary of what this release is about -->
+
+## Upgrading
+
+<!-- Here goes notes on how to upgrade from previous versions, including deprecations and what they should be replaced with -->
+
+## New Features
+
+<!-- Here goes the main new features and examples or instructions on how to use them -->
+
+## Bug Fixes
+
+<!-- Here goes notable bug fixes that are worth a special mention or explanation -->