fix: update Python devcontainer image to resolve Node 16

[mfagundez-4geeks]

Problem

When opening a new Codespace, learnpack start failed immediately with:

[ERR_REQUIRE_ESM]: require() of ES Module (...) not supported Error: command start not found

LearnPack 5.x depends on packages (e.g. syllable) that are ESM-only and
incompatible with Node 16.

Root cause

The base image mcr.microsoft.com/devcontainers/python:0-3.10 ships with
nvm and Node 16.20.2 pre-installed. When the node:1 dev container
feature runs and finds nvm already present, it attempts to install Node 22
on top of it, but the installation silently fails or does not update the
default alias. As a result, onCreateCommand runs npm install -g against
the only available Node version — 16 — and LearnPack 5.x ends up installed
in an incompatible runtime.

Fix

Replace the legacy base image with the current official variant:

- "image": "mcr.microsoft.com/devcontainers/python:0-3.10"
+ "image": "mcr.microsoft.com/devcontainers/python:3.10-bookworm"