[Client] Inconsistent `Default` vs `skip_serializing_none` usage for status pages

[CommanderStorm]

Hi, I just tried to use the client and I came across a bit of a weird API-decision.

I wanted to ask if the partial usage of skip_serializing_none and the partial usage of Default is intentional and If you'd like a PR for this (in either direction)

here Default is not implemented

https://github.com/BigBoot/AutoKuma/blob/8e16d11bc72f7c13e8ea97a13b9b68e8d72cfc40/kuma-client/src/models/status_page.rs#L62-L66

vs here Default is implemented

https://github.com/BigBoot/AutoKuma/blob/8e16d11bc72f7c13e8ea97a13b9b68e8d72cfc40/kuma-client/src/models/monitor.rs#L144-L148

The result is that the handy ..Default::default() shorthand does not work for all models.

PS: during trying the stus page I came acros this design decision:

https://github.com/BigBoot/AutoKuma/blob/8e16d11bc72f7c13e8ea97a13b9b68e8d72cfc40/kuma-client/src/models/status_page.rs#L81

=> this should be icon: String with a data:..-url. there is a patch for this in an upcoming release where we are going to accept urls there, but currently only data: