ci: migrate CI workflow to pnpm and node 24

Author: cblanc

.github/workflows/ci.yml

@@ -9,25 +9,23 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - name: Use Node.js 20
-        uses: actions/setup-node@v3
-        with:
-          node-version: 20.x
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v4
 
-      - name: Cache node modules
-        uses: actions/cache@v3
+      - name: Use Node.js 20
+        uses: actions/setup-node@v4
         with:
-          path: ~/.npm
-          key: ${{ runner.os }}-node-${{ hashFiles('**/package-lock.json') }}
+          node-version: 24.x
+          cache: pnpm
 
       - name: Install
-        run: npm install
+        run: pnpm install --frozen-lockfile
 
       - name: Lint spec
-        run: npm run test
+        run: pnpm test
 
       - name: Build
-        run: npm run build
+        run: pnpm build
 
       - name: Smoke test
         run: node smoke.js