add healthz endpoint for liveness probing

[Kariton]

Hey,

i just added your container to my helm chart for kubernetes deployments.
ill create a PR late to add it to the upstream helm chart here: SQLJames/factorio-server-charts
for liveness checks it is really useful to have probing endpoints like /healthz as described here:

https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/

[nekomeowww]

Ah, thanks, I will integrate them ASAP I finish my travel (2 days left)

[Kariton]

PR: SQLJames/factorio-server-charts#57

[nekomeowww]

Released https://github.com/nekomeowww/factorio-rcon-api/releases/tag/v1.1.0