Install pnpm in JS workflow

Author: harsha509

.github/workflows/nightly.yml

@@ -174,6 +174,9 @@ jobs:
       cache-key: javascript-nightly
       node-version: '22.x'
       run: |
+        # Install pnpm
+        npm install -g pnpm
+
         sed -i 's|https://registry.npmjs.org/|https://npm.pkg.github.com|g' javascript/selenium-webdriver/package.json
         sed -i 's|"name": "selenium-webdriver"|"name": "@seleniumhq/selenium-webdriver"|g' javascript/selenium-webdriver/package.json
         echo "//npm.pkg.github.com/:_authToken=${NODE_AUTH_TOKEN}" >> ~/.npmrc