chore: refactor python version

Author: saenyakorn

.github/workflows/benchmark.yaml

@@ -11,6 +11,7 @@ env:
   NODE_VERSION: 20.16.0
   PNPM_VERSION: 9.14.2
   BUN_VERSION: 1.1.10
+  PYTHON_VERSION: 3.13
 
 permissions:
   actions: read
@@ -60,7 +61,7 @@ jobs:
       - uses: actions/setup-python@v5
         id: setup_python
         with:
-          python-version: '3.13'
+          python-version: ${{ env.PYTHON_VERSION }}
           cache: 'pip'
 
       - name: Restore cached virtualenv