Update pnpm/action-setup action to v6

Author: renovate[bot]

.github/workflows/pr.yaml

@@ -17,7 +17,7 @@ jobs:
       - uses: actions/checkout@v6
 
       - name: Set up pnpm
-        uses: pnpm/action-setup@v4
+        uses: pnpm/action-setup@v6
         with:
           package_json_file: package.json