Change csv extractor filename trait type

Created by: martinRenou

It helps in the GUI, it displays the correct widget for file inputs

Created by: codecov[bot]

Codecov Report

Merging #80 into master will not change coverage. The diff coverage is 100%.

@@           Coverage Diff           @@
##           master      #80   +/-   ##
=======================================
  Coverage   95.68%   95.68%           
=======================================
  Files          49       49           
  Lines         719      719           
  Branches       55       55           
=======================================
  Hits          688      688           
  Misses         29       29           
  Partials        2        2

Impacted Files	Coverage Δ
...plugins/dummy/csv_extractor/csv_extractor_model.py	100% <100%> (ø)	⬆

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