Use GitHub generate-notes API for changelog

Produces the standard GitHub release notes format with PR links,
clean titles, and New Contributors section automatically.

Author: Kyle-Ye

.github/workflows/release.yml

@@ -62,16 +62,16 @@ jobs:
             echo "- ${{ steps.build_info.outputs.swift_version }}"
             echo ""
 
-            # What's Changed section
-            echo "## What's Changed"
+            # What's Changed section (auto-generated by GitHub)
             if [ -n "$PREV_TAG" ]; then
-              gh api "repos/${REPO}/compare/${PREV_TAG}...${TAG_NAME}" --paginate \
-                --jq '.commits[] | select(.parents | length == 1) | "* \(.commit.message | split("\n")[0]) by @\(if .author then .author.login else .commit.author.name end) in \(.html_url)"'
-              echo ""
-              echo "**Full Changelog**: ${GITHUB_SERVER_URL}/${REPO}/compare/${PREV_TAG}...${TAG_NAME}"
+              gh api "repos/${REPO}/releases/generate-notes" \
+                -f tag_name="${TAG_NAME}" \
+                -f previous_tag_name="${PREV_TAG}" \
+                --jq '.body'
             else
-              gh api "repos/${REPO}/commits" --paginate \
-                --jq '.[] | select(.parents | length <= 1) | "* \(.commit.message | split("\n")[0]) by @\(if .author then .author.login else .commit.author.name end) in \(.html_url)"'
+              gh api "repos/${REPO}/releases/generate-notes" \
+                -f tag_name="${TAG_NAME}" \
+                --jq '.body'
             fi
           } > release_notes.md
       - name: Create Release