Remove explicit pnpm version to use packageManager field

The package.json specifies [email protected] in packageManager field.
Removing explicit version from workflows to avoid version conflicts.

Author: timolins

.github/workflows/main.yml

@@ -10,8 +10,6 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - uses: pnpm/action-setup@v4
-        with:
-          version: 8
       - name: Use Node.js ${{ matrix.node-version }}
         uses: actions/setup-node@v4
         with:

.github/workflows/size.yml

@@ -8,8 +8,6 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - uses: pnpm/action-setup@v4
-        with:
-          version: 8
       - uses: actions/setup-node@v4
         with:
           node-version: 20.x