install pnpm for github action

Author: ElliotFriend

.github/workflows/test.yaml

@@ -17,6 +17,11 @@ jobs:
             - name: Checkout
               uses: actions/checkout@v4
 
+            - name: Install pnpm
+              uses: pnpm/action-setup@v4
+              with:
+                  version: 9
+
             - name: Use Node.js (20.x)
               uses: actions/setup-node@v4
               with: