`FileUpload` makes the Kernel die on `file_obj` read with (ipykernel > 6.29)

Description

When using the FileInput widget from ipyvuetify.extra, file uploads work as expected with ipykernel versions below 6.30. However, with ipykernel 6.30 and above, the widget no longer responds to file uploads and crashes the kernel.

Minimal example:

from ipyvuetify.extra import FileInput

def on_file_input_change(change):
    files = fi.get_files()
    for file in files:
        file["file_obj"].seek(0)
        file["file_obj"].read()

fi = FileInput()
fi.observe(on_file_input_change, names="file_info")
fi

Steps to reproduce:

Install ipykernel<6.30 and run the code above – file uploads work.
Upgrade to ipykernel>=6.30 and run the same code – file uploads work up to the read step and then kernel crashes.
Expected behavior: File uploads should work with newer versions of ipykernel.

Environment:

OS: Windows
ipyvuetify version: 1.11.3
ipykernel version: 6.30+ (broken), 6.29.5 (works)
Jupyter environment: [e.g., JupyterLab, VS Code, etc.]

Note

I also tested with ipykernel==7.0.0a1 and the kernel does not crash but the code fails differently:
AttributeError: 'IPythonKernel' object has no attribute 'msg_queue'

• Maybe also relevant for #288

Start by reproducing the minimal FileInput example with ipykernel 6.29.5 and 6.30+, focusing on get_files() and the file_obj read in the change callback. Inspect the FileInput implementation and the related context in #288 for ipykernel compatibility. Done means file uploads can be read without crashing the kernel on supported newer versions.