Default EMPflow config not running with Athena latest

@lesplend just noticed that with Athena, latest, there is a crash with the default config

dump-single-btag -c ../training-dataset-dumper/configs/EMPFlow.json -m 10 -o GN2v01_Run3.h5 mc23_13p6TeV.800030.Py8EG_A14NNPDF23LO_flatpT_Zprime_Extended.deriv.DAOD_FTAG1.e8514_s4162_r14622_p6368/DAOD_FTAG1.40769385._008587.pool.root.1

20240801_VMFv1_antikt4empflow_Alg                   FATAL Standard std::exception is caught in sysExecute
20240801_VMFv1_antikt4empflow_Alg                   ERROR Unsupported tensor shape for INT8 type
20240801_VMFv1_antikt4empflow_Alg                   ERROR Maximum number of errors ( 'ErrorMax':1) reached.

This is not present in 25.0.10.

Probably due to some recent ONNX update in Athena, interacting with the MaskFormer model introduced with !731 (merged)