Some errors in example `list.rs` on macOS

[xmh0511]

error[E0609]: no field `source` on type `Route`
  --> examples/list.rs:15:19
   |
15 |             route.source,
   |                   ^^^^^^ unknown field
   |
   = note: available fields are: `destination`, `prefix`, `gateway`, `ifindex`

error[E0609]: no field `source_prefix` on type `Route`
  --> examples/list.rs:16:19
   |
16 |             route.source_prefix,
   |                   ^^^^^^^^^^^^^ unknown field
   |
   = note: available fields are: `destination`, `prefix`, `gateway`, `ifindex`