MuoGeometryCnv: Increase threshold for reference comparison.

dumpAndCompare compares the calculated geometry with reference values. The threshold was a (single-precision) epsilon, but this was then giving a failure in aarch64, with a difference of almost exactly 1e-4. It turned out that that was coming from GeoDeDuplicator, where to consider two transforms equivalent, the translations must match to 1e-4. But if the difference is almost exactly 1e-4, then small FP differences can be magnified to just about 1e-4.

Fixes a test failure in MuonGeoModelTestR4 on aarch64.