Fix error propagation.

[pehamTom]

Description

There is an error in the computation of fault sets in state preparation circuits. Sometimes, the gates are not traversed in the correct topological order, and thus, some faults are not correct. This didn't show up before because the faults were still caught by the verification circuits.

Fixes # (issue)

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 83.5%. Comparing base (3cf545e) to head (7ad1ccc).
Report is 68 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #283     +/-   ##
=======================================
- Coverage   83.6%   83.5%   -0.1%     
=======================================
  Files         49      49             
  Lines       4159    4153      -6     
  Branches     372     372             
=======================================
- Hits        3477    3471      -6     
  Misses       682     682             

Flag	Coverage Δ		*Carryforward flag
cpp	83.6% <ø> (ø)		Carriedforward from 3cf545e
python	83.5% <100.0%> (-0.1%)	⬇️

*This pull request uses carry forward flags. Click here to find out more.

Files with missing lines	Coverage Δ
src/mqt/qecc/ft_stateprep/state_prep.py	71.9% <100.0%> (-0.3%)	⬇️

[lucasberent]

lgtm