[FR] add upgrade option to auto-cpufreq-installer

It would be nice if [auto-cpufreq-installer](https://github.com/AdnanHodzic/auto-cpufreq?tab=readme-ov-file#auto-cpufreq-installer) also supported updating/upgrading the service, so same logic can be used for installing & upgrading the service.

Or is the `--install` option already idempotent and could be used for upgrading?

Start with the referenced auto-cpufreq-installer entry point and inspect the existing --install behavior for an already installed service. Done means the installer supports the requested upgrade path using the same installation logic, with the resulting behavior verified and documented.

索引モデルが issue の本文から書いたものです。