build(deps): bump actions/setup-node (#47209)

Author: dependabot[bot]

.github/workflows/xpack-heartbeat-macos-unit-tests.yml

@@ -54,7 +54,7 @@ jobs:
     steps:
       - uses: actions/checkout@v5
 
-      - uses: actions/setup-node@v5
+      - uses: actions/setup-node@v6
         with:
           node-version: ${{ env.NODEJS_VERSION }}