fix: pandas 'nan' values when loading csv files

[brebuanirello-equinix]

Summary of Changes

Pandas detect missing values as default when reading a csv file. Due this configuration, Pandas was changing empty table and columns' descriptions to 'nan'. The solution is add one parameter when reading these csv files on pandas.read_csv( ) method
also passing na_filter=False can improve the performance of reading a large file.

Tests

N/A

Documentation

The documentation comes from oficial pandas lib

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