add monitoring to stats server

[alsuren]

Inspired by https://jvns.ca/blog/2022/07/09/monitoring-small-web-services/

https://github.com/upptime/upptime is probably more philosophically aligned with my current "how much can I get github actions to do for me for free?" philosophy.

I will probably also want this for the cargo-quickbuild server as well (https://github.com/cargo-quick/cargo-quick/issues/22 the quickbuild server will be more important, because it will cause service degradation if it is down)

[matthewruzzi]

Uptime Robot also provides a free plan with up to 50 monitors.

https://uptimerobot.com Demo status page: https://status.uptimerobot.com