ImGui::PlotLine doesn't rebuild itself.

Hi, for a school project we have to graph some data with imgui so I decided to use Implot.

```cpp
ImGui::Begin("Exercise 1");
if (ImGui::Button("Run benchmark", ImVec2(100, 20)))
{
BenchMarkExercise1();
}

if (ImPlot::BeginPlot("Exercise 1"))
{

ImPlot::SetupAxes("Allocation size", "Time");
ImPlot::PlotLine("Speed", m_Iterations.data(), m_Ex1Results.data(), (int)m_Iterations.size());
ImPlot::EndPlot();
}

ImGui::End();
```

m_Iterations is a vector of datatype double and so is m_Ex1Results. Both are initialized to hold the same size of data (10 points)

However when pressing the run benchmark button the graph doesn't display any of this new data.

Start by reproducing the example around ImGui::Button, ImPlot::BeginPlot, and ImPlot::PlotLine, then inspect how PlotLine receives updated vector data after BenchMarkExercise1() runs. Done means pressing “Run benchmark” causes the plot to display the new data without breaking the existing plot lifecycle.

Written by the indexing model from the issue text.