GitHub+scripts: add CI check for release notes

Author: guggero

.github/workflows/main.yaml

@@ -223,6 +223,20 @@ jobs:
       - name: run format
         run: make fmt
 
+  ########################
+  # check PR updates release notes
+  ########################
+  milestone-check:
+    name: Check release notes updated
+    runs-on: ubuntu-latest
+    if: '!contains(github.event.pull_request.labels.*.name, ''no-changelog'')'
+    steps:
+      - name: Git checkout
+        uses: actions/checkout@v4
+
+      - name: Release notes check
+        run: scripts/check-release-notes.sh
+
   ########################
   # run unit tests
   ########################

scripts/check-release-notes.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+
+set -e
+
+# Extract the PR number which is stored in the $GITHUB_REF env variable. The
+# format of the string stored in the variable is: refs/pull/:PRNUMBER/merge.
+PR_NUMBER=$(echo $GITHUB_REF | awk 'BEGIN { FS = "/" } ; { print $3 }')
+
+# If this is a PR being merged into the main repo, then the PR number will
+# actually be "master" here, so we'll ignore this case, and assume that in
+# order for it to be merged it had to pass the check in its base branch. If
+# we're trying to merge this with the Merge Queue, then the PR number will be
+# "gh-readonly-queue" instead.
+if [[ $PR_NUMBER == "master" ]] || [[ $PR_NUMBER == "gh-readonly-queue" ]]; then
+    exit 0
+fi
+
+# Ensure that the PR number at least shows up in the release notes folder under
+# one of the contained milestones.
+if ! grep -r -q "lightninglabs/taproot-assets/pull/$PR_NUMBER" docs/release-notes; then
+    echo "PR $PR_NUMBER didn't update release notes"
+    exit 1
+fi