[ci] Fix examples not building due to missing virtual functions

examples/Editor/example_graph.cpp

@@ -103,6 +103,7 @@ struct my_node final : ossia::graph_node
     m_outlets.push_back(new ossia::value_outlet);
   }
 
+  std::string label() const noexcept override { return "my_node"; }
   void run(const ossia::token_request& t, ossia::exec_state_facade) noexcept override
   {
     if(auto a_float = pop_value<float>(this->root_inputs()[0]))

examples/Network/OSCQuery_publication.cpp

@@ -195,7 +195,7 @@ int main()
   local_proto.expose_to(std::move(oscq));
 
   while(true)
-    ;
+    std::this_thread::yield();
 }
 
 void printValueCallback(const value& v)

src/ossia/dataflow/nodes/gain.hpp

@@ -18,6 +18,7 @@ struct gain_node final : public ossia::nonowning_graph_node
     m_outlets.push_back(&audio_out);
   }
 
+  std::string label() const noexcept override { return "gain"; }
   void run(const ossia::token_request& t, ossia::exec_state_facade st) noexcept override
   {
     auto& vals = gain_in.target<ossia::value_port>()->get_data();

src/ossia/dataflow/nodes/rand_float.hpp

@@ -18,6 +18,7 @@ struct rand_float final : public ossia::nonowning_graph_node
     m_outlets.push_back(&value_out);
   }
 
+  std::string label() const noexcept override { return "rand_float"; }
   void run(const ossia::token_request& t, ossia::exec_state_facade e) noexcept override
   {
     thread_local std::mt19937 gen;

src/ossia/dataflow/nodes/sine.hpp

@@ -23,6 +23,8 @@ struct sine final : public ossia::nonowning_graph_node
     m_inlets.push_back(&freq_in);
     m_outlets.push_back(&audio_out);
   }
+
+  std::string label() const noexcept override { return "sine"; }
   void run(const ossia::token_request& t, ossia::exec_state_facade st) noexcept override
   {
     auto& vals = freq_in.target<ossia::value_port>()->get_data();