update tables demo to use TableHeadersRow

Author: epezent

implot_demo.cpp

@@ -1129,7 +1129,7 @@ void ShowDemoWindow(bool* p_open) {
             ImGui::TableSetupColumn("Electrode", ImGuiTableColumnFlags_WidthFixed, 75.0f);
             ImGui::TableSetupColumn("Voltage", ImGuiTableColumnFlags_WidthFixed, 75.0f);
             ImGui::TableSetupColumn("EMG Signal");
-            ImGui::TableAutoHeaders();
+            ImGui::TableHeadersRow();
             ImPlot::PushColormap(ImPlotColormap_Cool);
             for (int row = 0; row < 10; row++) {
                 ImGui::TableNextRow();