bump structopt version

Bump structopt to finish ticket #134 (closed)

bin/dunitrust-server/src/main.rs

@@ -16,6 +16,8 @@
 //! Main function for classic Dunitrust nodes (no specialization).
 
 #![deny(
+    clippy::option_unwrap_used,
+    clippy::result_unwrap_used,
     missing_docs,
     missing_debug_implementations,
     missing_copy_implementations,