Implement rate limiting and backoff for UptimeRobot

[invidian]

Similar to #106, it would be nice if controller could have a max req per minute setting and could respect a retry-After header, to avoid printing a lot of 429 errors for free UptimeRobot accounts.

[github-actions]

This issue is stale because it has been open for 60 days with no activity.

[invidian]

not stale please

[github-actions]

This issue is stale because it has been open for 60 days with no activity.

[github-actions]

This issue was closed because it has been inactive for 30 days since being marked as stale.

[karl-johan-grahn]

Reopening issues that inadvertently were closed as stale

[github-actions]

This issue is stale because it has been open for 60 days with no activity.