adapt error message on ENODEV test for neli 0.5+

Related to gluxon#28 which introduced this test.

Since at least 0.5.3 the ENODEV is propagated, causing this test
to fail:

    ---- missing_device_returns_sensible_error stdout ----
    thread 'missing_device_returns_sensible_error' panicked at 'assertion failed: `(left == right)`
      left: `"Error response received from netlink: Unknown error -19 (os error -19)"`,
     right: `"No ack received"`', tests/enodev.rs:30:5
    note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

tests/enodev.rs

@@ -27,7 +27,12 @@ fn missing_device_returns_sensible_error() -> anyhow::Result<()> {
     // TODO: Ensure this library returns more sensible errors. Update the "No
     // ack received" string below to "No device found by interface name or
     // public key".
-    assert_eq!(existing_err_message, "No ack received");
+    // As of neli 0.5.3 the library returns ENODEV instead of “No ack
+    // received”.
+    assert_eq!(
+        existing_err_message,
+        "Error response received from netlink: Unknown error -19 (os error -19)"
+    );
 
     Ok(())
 }