Update Node.js version from 20 to 22 in ESLint workflow

Author: auttomus

.github/workflows/eslint.yml

@@ -38,7 +38,7 @@ jobs:
       - name: Setup Node.js
         uses: actions/setup-node@v4
         with:
-          node-version: 20
+          node-version: 22
           cache: pnpm
           cache-dependency-path: backend/pnpm-lock.yaml