v2.123.0

This release removes a potential panic: it was assumed that looking up a
socket's peer address was infallible, but in practice this call can
fail when a host is under high load. Now these failure only impact the
connection-level task and not the whole proxy proces.

Also, the `process_cpu_seconds_total` metric is now exposed as a float
so that its value may include fractional seconds with 10ms granularity.