chore: update pnpm setup in CI workflow

- Replace pnpm/action-setup with corepack commands
- Enable corepack and prepare pnpm@8
- Remove trailing newline in env section

Author: huzijie.sea

.github/workflows/ci.yml

@@ -25,10 +25,11 @@ jobs:
         node-version: ${{ matrix.node-version }}
         cache: 'pnpm'
 
-    - name: Setup pnpm
-      uses: pnpm/action-setup@v4
-      with:
-        version: 8
+    - name: Enable corepack
+      run: corepack enable
+
+    - name: Install pnpm
+      run: corepack prepare pnpm@8 --activate
 
     - name: Install dependencies
       run: pnpm install
@@ -59,10 +60,11 @@ jobs:
         node-version: '20.x'
         cache: 'pnpm'
 
-    - name: Setup pnpm
-      uses: pnpm/action-setup@v4
-      with:
-        version: 8
+    - name: Enable corepack
+      run: corepack enable
+
+    - name: Install pnpm
+      run: corepack prepare pnpm@8 --activate
 
     - name: Install dependencies
       run: pnpm install
@@ -89,10 +91,11 @@ jobs:
         node-version: ${{ matrix.node-version }}
         cache: 'pnpm'
 
-    - name: Setup pnpm
-      uses: pnpm/action-setup@v4
-      with:
-        version: 8
+    - name: Enable corepack
+      run: corepack enable
+
+    - name: Install pnpm
+      run: corepack prepare pnpm@8 --activate
 
     - name: Install dependencies
       run: pnpm install
@@ -105,4 +108,4 @@ jobs:
 
 env:
   CI: true
-  NODE_ENV: test
+  NODE_ENV: test