fix: respect OCCT precision in npdet_to_step

[wdconinc]

Briefly, what does this PR introduce?

This PR fixes failing exports for cylinders/cones with differences in rmin or rmax that are smaller than OCCT's internal Precision::Confusion(), but still not larger than std::numeric_limits<double>::epsilon().

What kind of change does this PR introduce?

• [x] Bug fix (issue https://github.com/eic/epic/actions/runs/8609642440/job/23593952079?pr=661#step:5:125)
• [ ] New feature (issue #__)
• [ ] Documentation update
• [ ] Other: __

Please check if this PR fulfills the following:

• [ ] Tests for the changes have been added
• [ ] Documentation has been added / updated
• [ ] Changes have been communicated to collaborators

Does this PR introduce breaking changes? What changes might users need to make to their code?

No.

Does this PR change default behavior?

No.