CI: Switch to ARM runners, update to Ubuntu 24.04 (#4823)* CI: Catch bad whitelist.txt entriesAs worked out by @User123698745 inhttps://github.com/RSS-Bridge/rss-bridge/pull/4792#issuecomment-3478187416Introduced in 9e24ad8f.* CI: Switch all to ubuntu-24.04-arm runnersIn my experience, the ARM runners are measurably faster on compute-heavyjobs. PHP should work as before. The container build uses QEMU anyways,so the host CPU architecture only matters in performance.This also upgrades old Ubuntu 22.04 runners to 24.04.