Update syntax highlighting for Python

[d3z-the-dev]

Is it possible to add syntax highlighting for walrus operator and pattern matching ?

[Monokai]

The walrus operator is colored like a keyword, pattern matching might be difficult, as it probably depends on the syntax definitions of Sublime Text. Color themes depend on syntax definitions to be able to highlight different parts of code in a different color. Do you have an example of things that go wrong?