message: generator: Do not use deprecated np.str type
  See
diff: @@ -248,7 +248,7 @@ def process_file(filename, namedtup):
  # Mapping is: All elements of the line grouped by the first column
  path = os.path.join(csv_dir, filename)
  - df = pd.read_csv(path, comment='#', dtype=np.str)
  + df = pd.read_csv(path, comment='#', dtype=str)
  df = df.fillna("")
  lines = [ list(r) for _i, r in df.iterrows() ]
  