Update to Node.js 24

[nigelcharman]

I'm seeing this warning on GitHub Actions:

Warning: Node.js 20 actions are deprecated. The following actions are running on Node.js 20 and may not work as expected: MathRobin/timezone-action@v1.1. Actions will be forced to run with Node.js 24 by default starting June 2nd, 2026. Node.js 20 will be removed from the runner on September 16th, 2026.

Are you able to update this action to Node.js 24 please?

[nigelcharman]

I've found using the TZ environment variable in GitHub Actions workflows works for me, so have removed this action from my workflows.