Ensure port in listenany stays UInt16 (JuliaLang#47213)

As reported [here](https://discourse.julialang.org/t/test-failures-for-sockets-base-runtests-sockets/88898).

My guess on the original issue reported is that, for some reason, the host where the tests are run
is unable to listen on any ports, so we end up cycling through the entire UInt16 range (the test
starts at port 11011), but when we fail on port 65535, we do `addr.port + 1` and instead of wrapping
around as I believe this function intends to happen (as noted by the `addr.port == default_port` check
before we error), it gets promoted to `Int(65536)` which then throws an (unexpected) error in the `InetAddr`
constructor.

I'm not quite sure how to test this exactly though, because we'd need to simulate not being able
to listen on any ports? If anyone has any ideas, I'm all ears.

stdlib/Sockets/src/Sockets.jl

@@ -727,7 +727,7 @@ function listenany(host::IPAddr, default_port; backlog::Integer=BACKLOG_DEFAULT)
  return (addr.port, sock)
  end
  close(sock)
- addr = InetAddr(addr.host, addr.port + 1)
+ addr = InetAddr(addr.host, addr.port + UInt16(1))
  if addr.port == default_port
  error("no ports available")
  end