The /os/info API endpoint has been using D-Bus property TimeUSec which got
cached between requests, so the time returned was not always the same as
current time on the host system at the time of the request. Since there's no
reason to use D-Bus API for the time, as Supervisor runs on the same machine
and time is global, simply format current datetime object with Python and
return it in the response.
Fixes#6581
6a955527f3