Bump parent pom

Updated to pom-imagej 2.51
Update for populateInputCandidates

The MATLABDatasetConverter will now populate input candidates when
MatlabNumericArray outputs are requested. It will use the ObjectIndex's
currently available Datasets as the potential candidates

This allows a WidgetModel typed on MatlabNumericArray to know that the
available Datasets should be used as choices displayed to a user when
filling in parameters for a mult-param script, for example.