README example 1 error at `pytable(iris)`

**Affects:** PythonCall

**Describe the bug**
Running Pluto notebook and attempting to reproduce Example 1 in the README. `pytable(iris)` errors with:
`Python: Julia: ArgumentError: Unordered CategoricalValue objects cannot be tested for order using <. Use isless instead, or call the ordered! function on the parent array to change this`

**Your system**
Ubuntu 25.10
Pluto v1.0.1

Pkg.status() ***
[992eb4ea] CondaPkg v0.2.36
[6099a3de] PythonCall v0.9.35
[ce6b1742] RDatasets v0.8.1
[44cfe95a] Pkg v1.12.1

CondaPkg.status() ***
seaborn v0.13.2

perhaps a known issue related to issue #88

line reference:
https://github.com/JuliaPy/PythonCall.jl/blob/e477d4d805f5136c274576cc37cea6101bebe4c5/examples/seaborn.jl#L20

Start by reproducing README Example 1 in a Pluto notebook and inspect examples/seaborn.jl at line 20, where pytable(iris) is called. Confirm the reported CategoricalValue error with the listed environment. Done means the README example runs successfully without this error.

索引モデルが issue の本文から書いたものです。