ci: remove pnpm version specification from workflow

Author: thetarnav

.github/workflows/tests.yml

@@ -17,8 +17,6 @@ jobs:
           fetch-depth: 0
 
       - uses: pnpm/action-setup@v4
-        with:
-          version: 9
 
       - name: Setup Node.js environment
         uses: actions/setup-node@v4