chore: use explicit pnpm 9 version for reproducibility (#873)

.github/workflows/lint.yml

@@ -13,7 +13,7 @@ jobs:
     - name: Install pnpm
       uses: pnpm/action-setup@v4
       with:
-        version: 9
+        version: 9.12.3
     - name: Use Node.js ${{ matrix.node-version }}
       uses: actions/setup-node@v4
       with:

package.json

@@ -103,5 +103,6 @@
     "tailwindcss": "^3.4.1",
     "tsx": "^4.19.1",
     "typescript": "^5.6.3"
-  }
+  },
+  "packageManager": "pnpm@9.12.3"
 }