Tabulator column grouping when column names are numeric

[thuydotm]

ALL software version info

panel 0.13.0a19
bokeh 2.4.2

Description of expected behavior and the observed behavior

When grouping columns with Tabulator, if the column names are of numeric dtype then they are not grouped properly.

Complete, minimal, self-contained example code that reproduces the issue

import panel as pn
import pandas as pd

df = pd.DataFrame({
    1.0   : [1, 2, 3],
    2.0   : [1, 2, 3],
    3     : [1, 2, 3],
    'str1': [1, 2, 3],
    'str2': [1, 2, 3],
})

table = pn.widgets.Tabulator(
    value=df,
    disabled=False,
    layout='fit_data_stretch',
    groups = {
        'numbers': df.columns[:3],
        'others': df.columns[3:],
    }
)

tmpl = pn.template.MaterialTemplate()
tmpl.main.append(table)
tmpl.servable()