Fix Quick Start rendering in README

[asukhodko]

Motivation

• The Quick Start example contained a fenced Python block that included a nested Markdown code fence which prevented correct rendering.
• The README's example needed to allow nested triple-backtick fences inside the shown Python string literal.

Description

• Updated README.md Quick Start example to use a four-backtick fence for the Python example (````python / ````) so the inner ```python ``` block renders correctly.
• The change is limited to the documentation example and does not affect library code or behavior.

Testing

• No automated tests were run because this is a docs-only change.
• Documentation rendering build was not executed as part of this change.

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Codex Task