Merge pull request #4901 from UniversityOfHelsinkiCS/renovate/actions-setup-node-6.x

Update actions/setup-node action to v6

Author: santeri0200

.github/actions/lint/action.yaml

@@ -4,7 +4,7 @@ description: 'Runs ESLint and Stylelint for frontend and backend'
 runs:
   using: composite
   steps:
-    - uses: actions/setup-node@v5
+    - uses: actions/setup-node@v6
       with:
         node-version: 22
     - name: 'Install dependencies'

.github/workflows/updater.yaml

@@ -21,7 +21,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v5
-      - uses: actions/setup-node@v5
+      - uses: actions/setup-node@v6
         with:
           node-version: 22
       - name: 'Install dependencies'