Add pnpm installation step to CI workflow

Author: py-dev-nandini-12

.github/workflows/main.yml

@@ -43,6 +43,9 @@ jobs:
       - name: Checkout Code
         uses: actions/checkout@v3
 
+      - name: Install pnpm
+        run: npm install -g pnpm
+
       - name: Install Dependencies
         run: pnpm install