use pgfplots instead of pgfplotstable

gen-boxplots.py

@@ -10,7 +10,7 @@ def parse_data(stream):
 TIKZ_TEMPLATE = \
 """
 \\documentclass[crop=false]{standalone}
-\\usepackage{pgfplotstable}
+\\usepackage{pgfplots}
 \\pgfplotsset{compat=1.17}
 \\usepgfplotslibrary{statistics}
 \\begin{document}