chore(llc): prepare for 0.3.1 release

[renefloor]

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• The code changes follow best practices
• Code changes are tested (add some information if not applicable)

Description of the pull request

This prepares for the 0.3.1 release. It also adds a dart_fix file for the newly deprecated methods.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 3.24%. Comparing base (3295f49) to head (e14b2f3).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main     #48   +/-   ##
=====================================
  Coverage   3.24%   3.24%           
=====================================
  Files        120     120           
  Lines       3271    3271           
=====================================
  Hits         106     106           
  Misses      3165    3165           

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