aquatic_ws: in remove_inactive_connections, run shrink_to_fit on map

TODO.md

@@ -4,7 +4,6 @@
 * network
   * native_tls for wss support
   * handshake: deregister stream when applicable
-  * connection cleaning: shrink to fit
 * test
   * test full torrent transfer (offer-answer exchange)
 * torrent state cleaning

aquatic_ws/src/lib/network.rs

@@ -98,6 +98,8 @@ pub fn remove_inactive_connections(
             true
         }
     });
+
+    connections.shrink_to_fit();
 }