ci: use actions/setup-node@v6

Author: AviVahl

.github/workflows/tests.yml

@@ -11,7 +11,7 @@ jobs:
         os: [ubuntu-latest, windows-latest, macOS-latest]
     steps:
       - uses: actions/checkout@v5
-      - uses: actions/setup-node@v4
+      - uses: actions/setup-node@v6
         with:
           node-version-file: .nvmrc
       - run: npm ci