fix: handle jupyter-kernel-client >= 1.0.0 KernelClient rename

[dpaul0501]

Problem

jupyter-kernel-client v1.0.0 renamed KernelClient → JupyterKernelClient. The else branch in runtime.py still references the old name, causing every colab run, colab exec, colab install, and colab sessions command to fail with:

AttributeError: module 'jupyter_kernel_client' has no attribute 'KernelClient'

This affects any user who has jupyter-kernel-client >= 1.0.0 installed (e.g. via Homebrew Python or a fresh pip install).

Fix

Use getattr with a fallback to JupyterKernelClient so both old (< 1.0.0) and new (>= 1.0.0) versions of the dependency work:

_KernelCls = getattr(
    jupyter_kernel_client, "KernelClient", None
) or jupyter_kernel_client.JupyterKernelClient
self._kernel_client = _KernelCls(...)

Tested

Verified on macOS with jupyter-kernel-client==1.0.2 — colab sessions and colab run no longer throw AttributeError.

🤖 Generated with Claude Code

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[sethtroisi]

#125 merged and fixes the issue.