Replace Node setup action with pnpm setup action

Author: Nick-Lemy

.github/workflows/main.yaml

@@ -10,9 +10,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
-      - uses: actions/setup-node@v3
+      - uses: pnpm/action-setup@v4
         with:
-          node-version: 20
+          version: 9
 
       - name: Install dependencies
         run: pnpm ci install