Cleaning up minor warnings

[kogut]

This cleans up these gcc warnings, mostly related to moving to the newer API of zmq vs. deprecated function use:

NodeState.cpp:51:34: warning: comparison of integer expressions of different signedness: ‘QtNodes::PortIndex’ {aka ‘int’} and ‘std::vector<std::unordered_map<QUuid, QtNodes::Connection*> >::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   51 |   if( portIndex < 0 || portIndex >= connections.size() )
sidepanel_monitor.cpp:42:42: warning: ‘bool zmq::detail::socket_base::recv(zmq::message_t*, int)’ is deprecated: from 4.3.1, use recv taking a reference to message_t and recv_flags [-Wdeprecated-declarations]
   42 |         while(  _zmq_subscriber.recv(&msg) )
sidepanel_monitor.cpp:1:
/usr/include/zmq.hpp:1407:10: note: declared here
 1407 |     bool recv(message_t *msg_, int flags_ = 0)
sidepanel_monitor.cpp:127:32: warning: ‘bool zmq::detail::socket_base::send(zmq::message_t&, int)’ is deprecated: from 4.3.1, use send taking message_t and send_flags [-Wdeprecated-declarations]
  127 |         zmq_client.send(request);
sidepanel_monitor.cpp:1:
/usr/include/zmq.hpp:1326:10: note: declared here
 1326 |     bool send(message_t &msg_,
sidepanel_monitor.cpp:129:47: warning: ‘bool zmq::detail::socket_base::recv(zmq::message_t*, int)’ is deprecated: from 4.3.1, use recv taking a reference to message_t and recv_flags [-Wdeprecated-declarations]
  129 |         bool received = zmq_client.recv(&reply);
sidepanel_monitor.cpp:1:
/usr/include/zmq.hpp:1407:10: note: declared here
 1407 |     bool recv(message_t *msg_, int flags_ = 0)

[kogut]

I don't believe the failed check is related to the PR. CI appears to be broken.