Fix an issue with wrong leg fusers

[lkdvos]

@AFeuerpfeil let me know if this resolves the issue 😇

[AFeuerpfeil]

Thanks, I will check.

[codecov]

Codecov Report

❌ Patch coverage is 63.15789% with 7 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/algorithms/derivatives/mpo_derivatives.jl	63.15%	7 Missing ⚠️

Files with missing lines	Coverage Δ
src/algorithms/derivatives/mpo_derivatives.jl	77.46% <63.15%> (+0.02%)	⬆️

... and 1 file with indirect coverage changes

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• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[AFeuerpfeil]

The first set of benchmarks worked. I will now go the other dataset that I sent you yesterday.

[AFeuerpfeil]

Perfect, everything is working now and the output (with the exception of the iteration time ;)) from main and 0.13.10 agree up to numerical precision.