Update actions/setup-node action to v5

Author: renovate[bot]

.github/workflows/repomix.yml

@@ -26,7 +26,7 @@ jobs:
           sleep 300
 
       - name: Setup Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v5
         with:
           node-version: "22"