chore: change backend for emoji generation

[Anselmoo]

This pull request includes a small change to the mkdocs.yml file. The change updates the emoji_index and emoji_generator settings to use the correct module paths for the material.extensions.emoji module instead of the deprecated materialx.emoji module.

• mkdocs.yml: Updated emoji_index and emoji_generator settings to use material.extensions.emoji module.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.12%. Comparing base (47336cb) to head (f57a946).
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #104   +/-   ##
=======================================
  Coverage   84.12%   84.12%           
=======================================
  Files          28       28           
  Lines        2400     2400           
=======================================
  Hits         2019     2019           
  Misses        381      381           

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