Kernel crash on Jupyter Notebook

**Describe the bug**

When I try to run the example code on a Jupyter Notebook:

```python
import pandas as pd
from pandasgui import show
df = pd.DataFrame(([[1, 2, 3], [4, 5, 6], [7, 8, 9]]), columns=['a', 'b', 'c'])
show(df)
```
I get `The kernel appears to have died. It will restart automatically.`

**Environment**
OS: Ubuntu 18.04
Python: 3.7.4
IDE: Jupyter Notebook

**Package versions**
```
django-plotly-dash==1.0.1
ipython==7.7.0
ipython-genutils==0.2.0
jupyter==1.0.0
jupyter-client==5.3.4
jupyter-console==6.0.0
jupyter-contrib-core==0.3.3
jupyter-contrib-nbextensions==0.5.1
jupyter-core==4.6.1
jupyter-highlight-selected-word==0.2.0
jupyter-latex-envs==1.4.6
jupyter-nbextensions-configurator==0.4.1
jupyter-plotly-dash==0.2.1
jupyterlab==1.1.4
jupyterlab-server==1.0.6
notebook==6.0.0
pandasgui==0.2.10.1
plotly==4.14.3
PyQt5==5.15.4
PyQt5-Qt5==5.15.2
PyQt5-sip==12.8.1
PyQtWebEngine==5.15.4
PyQtWebEngine-Qt5==5.15.2
```