Skip unchanged cached subtrees when removing nested nulls - #856

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@8ade135a41bc03ea155e62e844d188df1ea18608, actions/setup-node@cdca7365b2dadb8aad0a33bc7601856ffabcc48e, actions/upload-artifact@2848b2cda0e5190984587ec6bb1f36730ca78d50, nick-fields/retry@ce71cc2ab81d554ebbe88c79ab5975992d79ba08. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/