Add opt-in background refresh before cache expiry - #5

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830, actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5, actions/setup-java@c1e323688fd81a25caa38c78aa6df2d33d3e20d9, DeLaGuardo/setup-clojure@1fb06179c376b10a4da4c778e1c794ef5a0df302. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/