fix(ci): correct pnpm setup order in GitHub Actions

- Move pnpm installation before Node.js setup to avoid cache issues
- Add run_install: false to prevent automatic installation
- This fixes the 'Unable to locate executable file: pnpm' error

Author: vergissberlin

.github/workflows/ci.yml

@@ -13,17 +13,18 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
 
+      - name: Install pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          version: 9.12.0
+          run_install: false
+
       - name: Setup Node.js
         uses: actions/setup-node@v4
         with:
           node-version: '20'
           cache: 'pnpm'
 
-      - name: Install pnpm
-        uses: pnpm/action-setup@v4
-        with:
-          version: 9.12.0
-
       - name: Install dependencies
         run: pnpm install --frozen-lockfile