text: Title: use IFrame to display embedded D3 plot
  Body: when generating a pipeline plot with the D3 backend with `output='embed'`:
  
  https://github.com/ploomber/ploomber/blob/77d7dbf6b143ee17f886f76b6f3163d0ad5a39c9/src/ploomber/dag/dag.py#L893
  
  we use the requests-html library to load the HTML file since we need to execute the embedded JS for the plot to display:
  
  https://github.com/ploomber/ploomber/blob/77d7dbf6b143ee17f886f76b6f3163d0ad5a39c9/src/ploomber/dag/plot.py#L66
  
  and then we render the plot with a `IPython.display.HTML` object, this allows us to embed the plot in Jupyter. However, as pointed in https://github.com/ploomber/projects/issues/42 IPython has an `IFrame` object that correctly displays HTML and runs JS.
  
  We should remove the requests-html code and substitute it for using `IFrame`
  