ci: upgrade Python version to latest security release

Potentially need a Python version built with a newer version of glibc: https://github.com/differentiable-swift/swift-differentiation-benchmarks/actions/runs/17434492323/job/49500577731

Author: loonatick-src

.github/workflows/benchmark.yml

@@ -27,7 +27,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
-          python-version: "3.11"
+          python-version: "3.13"
       - name: Verify Python version
         run: python --version
       - name: Install dependencies