npm -> pnpm for SDK tests

Author: dylburger

.github/workflows/pipedream-sdk-test.yaml

@@ -24,9 +24,9 @@ jobs:
           node-version: '18'
 
       - name: Install dependencies
-        run: npm install
+        run: pnpm install
         working-directory: packages/sdk
 
       - name: Run tests
-        run: npm test
+        run: pnpm test
         working-directory: packages/sdk