fix a test waiting for IPv6 addr

[keepsimple1]

The latest main branch CI test is not stable on Windows:

Run: https://github.com/keepsimple1/mdns-sd/actions/runs/8678439543/job/23795359546

Error:

---- service_without_properties_with_alter_net_v6 stdout ----
Registered service with host_ip: [fe80::f9d5:d80:1f67:7226, ff:1:1:1:1:1:1:1]
Received event SearchStarted("_serv-no-prop._tcp.local. on addrs [10.1.0.64, fe80::f9d5:d80:1f67:7226, fe80::4ba1:7266:e46e:c2dc, 172.29.80.1]")
Received event ServiceFound("_serv-no-prop._tcp.local.", "1713070959023708._serv-no-prop._tcp.local.")
Resolved a service of 1713070959023708._serv-no-prop._tcp.local. addr(s): {10.1.0.[64](https://github.com/keepsimple1/mdns-sd/actions/runs/8678439543/job/23795359546#step:7:65)}
thread 'service_without_properties_with_alter_net_v6' panicked at 'assertion failed: `(left == right)`
  left: `0`,
 right: `1`', tests\mdns_test.rs:348:25

This patch is to make this test more stable and detect real issues if the test fails.