Added warning in README, as fix to issue 24

[KevinMTO]

This Pull Request makes the following changes:

• Fixes ⚠️ Deprecation Notice #24

Checklist:

• Changed README with warning.
• Development of the code of this repository continues in the mqt-qudits repository.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 67.2%. Comparing base (f775b69) to head (09ae062).

Additional details and impacted files

@@          Coverage Diff          @@
##            main     #25   +/-   ##
=====================================
  Coverage   67.2%   67.2%           
=====================================
  Files         16      16           
  Lines       2270    2270           
  Branches     377     377           
=====================================
  Hits        1527    1527           
  Misses       743     743           

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[burgholzer]

Great many thanks. I just adjusted the PR description so that it automatically links to the issue (it should be "Fixes #" instead of "Fixes issue ...").

Once this PR is merged, please archive the repository from the repository settings page on GitHub.