fix: remove explicit pnpm version from CI to use packageManager field

Author: marklearst

.github/workflows/ci.yml

@@ -12,8 +12,6 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - uses: pnpm/action-setup@v4
-        with:
-          version: 9
       - uses: actions/setup-node@v4
         with:
           node-version: 20