Update Node.js version to 20 and use pnpm for dependency installation

.github/workflows/docker-image.yaml

@@ -13,16 +13,35 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
 
-      - name: Set up Nodejs
-        uses: actions/setup-node@v3
+      - name: Install Node.js
+        uses: actions/setup-node@v4
         with:
-          node-version: 18
+          node-version: 20
+
+      - uses: pnpm/action-setup@v3
+        name: Install pnpm
+        with:
+          version: 8
+          run_install: false
+
+      - name: Get pnpm store directory
+        shell: bash
+        run: |
+          echo "STORE_PATH=$(pnpm store path --silent)" >> $GITHUB_ENV
+
+      - uses: actions/cache@v4
+        name: Setup pnpm cache
+        with:
+          path: ${{ env.STORE_PATH }}
+          key: ${{ runner.os }}-pnpm-store-${{ hashFiles('**/pnpm-lock.yaml') }}
+          restore-keys: |
+            ${{ runner.os }}-pnpm-store-
 
       - name: Install dependencies
-        run: npm install
+        run: pnpm install
 
       - name: Build
-        run: npm run build
+        run: pnpm build
         env:
           VITE_APP_BACKEND_BASEURL: https://api.tmpf.me