fix: add pnpm setup to Speakeasy workflow

Speakeasy internally runs pnpm install which requires pnpm to be
installed in the CI environment.

Author: mattapperson

.github/workflows/speakeasy_run_on_pr.yaml

@@ -20,6 +20,17 @@ jobs:
           ref: ${{ github.event.pull_request.head.ref }}
           token: ${{ secrets.GITHUB_TOKEN }}
 
+      - name: Install pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          version: 10
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '22'
+          cache: 'pnpm'
+
       - name: Install Speakeasy CLI
         run: |
           curl -fsSL https://raw.githubusercontent.com/speakeasy-api/speakeasy/main/install.sh | sh