Migrate coverage pipeline to score_coverage 0.3.1 - #450

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683, actions/setup-python@v5, actions/upload-artifact@v4, bazel-contrib/setup-bazel@0.15.0. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/