Upgrade Node.js setup action to version 6

Author: jacobdalamb

.github/workflows/check-pr-links.yml

@@ -15,7 +15,7 @@ jobs:
           fetch-depth: 0
 
       - name: Setup Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v6
         with:
           node-version: "20"