🔥 drop Python 3.8 support

[burgholzer]

Description

Python 3.8 will reach end of live in October 2024.
Qiskit is already issuing deprecation warnings since a couple of releases when using it on Python 3.8.
This PR officially drops support for Python 3.8 in mqt-ddsim.

Checklist:

• The pull request only contains commits that are related to it.
• I have added appropriate tests and documentation.
• I have made sure that all CI jobs on GitHub pass.
• The pull request introduces no new warnings and follows the project's style guidelines.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.3%. Comparing base (4409d5d) to head (4c2166a).
Report is 53 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #427   +/-   ##
=====================================
  Coverage   92.3%   92.3%           
=====================================
  Files         37      37           
  Lines       2721    2721           
  Branches     305     305           
=====================================
  Hits        2512    2512           
  Misses       209     209           

Flag	Coverage Δ
cpp	94.0% <ø> (ø)
python	87.4% <100.0%> (ø)

Files with missing lines	Coverage Δ
src/mqt/ddsim/provider.py	83.3% <100.0%> (ø)

... and 1 file with indirect coverage changes