fix: specify pnpm version 9 in publish workflow

Author: monadoid

.github/workflows/publish-pypi.yml

@@ -61,6 +61,8 @@ jobs:
 
       - name: Setup pnpm
         uses: pnpm/action-setup@v4
+        with:
+          version: 9
 
       - name: Setup Node.js
         uses: actions/setup-node@v4