auto_fit_columns not working when setting data

[ollyhensby]

Describe the bug When setting data with auto_fit_columns set to True, the columns do not autofit.

To Reproduce Steps to reproduce the behavior:

1. Run the following to set up a simple DataGrid with some dummy data.

   
   from ipydatagrid import DataGrid
   import pandas as pd

df = pd.DataFrame([{"An Important Title": 1}])

grid = DataGrid(df, auto_fit_columns=True, layout={"height": "50px"}) display(grid)

![image](https://github.com/bloomberg/ipydatagrid/assets/79875276/b6635f0f-af31-4f4c-9c26-5c55a69f7c48)

2. Then run the following to update the data:
```python
df = pd.DataFrame([{"An Important Title": 1, "Another Title": 2}])
grid.data = df

3. We see that the columns are no longer autofitting even though it is set to True.

Expected behavior Expect that new data is set and the columns are autofit e.g. for the example above I expect to see:

Environment (please complete the following information):

• Operating System and Version: Ubuntu Linux 20.04
• Browser [e.g. Firefox, Safari] (if applicable): Google Chrome Version 117.0.5938.132 (Official Build) (64-bit)

Additional context If display(grid) is executed again then it seems to sort itself out as expected:

[ollyhensby]

Closing as the pull request with the fix has been merged to the main branch.