[Feature Request] syntax coloring of Python f-strings by default

Description of the problem or steps to reproduce

Current behavior of micro is to treat Python f-strings like plain strings (yellow in the default color scheme):

This example is taken from https://docs.python.org/3/reference/lexical_analysis.html#f-strings where the variables like name in the first f-string of this example are in white (screenshot with Firefox showing coloring of the expressions with f-strings):

Desired behaviour would be like the Python.org documentation, or similar - this is Sublime Text Build 4189 on macOS which seems to format the code snippets within f-strings like normal Python code:

Specifications

$ micro --version
Version: 2.0.14
Commit hash: 04c57704
Compiled on August 27, 2024

Commit hash: 04c57704
OS: Linux
Terminal: Ghostty

(Same behavior on macOS with micro 2.0.14)

No implementation file or test is named. Start by locating micro's Python syntax-highlighting rules and reproduce the documented f-string examples; compare how expressions inside f-strings are currently classified. Done means Python f-strings visibly highlight their embedded expressions by default, with relevant syntax-highlighting tests updated if they exist.