Simplify test_DerivativesDataSink_data_dtype_source
Simplify test_DerivativesDataSink_data_dtype_source

Co-authored-by: Chris Markiewicz <985f67effdb40e64a0270743b2fa0fb4d285bc9c@gmail.com>
poldracklab/niworkflows,oesteban/niworkflows,oesteban/niworkflows,oesteban/niworkflows,poldracklab/niworkflows