style of extra_groupstyle_parameters in signature of get_tikz_code wrong

[felinae98]

According to

tikzplotlib/src/tikzplotlib/_axes.py

Lines 453 to 454 in 450712b

	group_style = [f"group size={geom[1]} by {geom[0]}"]
	group_style.extend(data["extra groupstyle options [base]"])

the type of extra_groupstyle_parameters should be list[str], but in

tikzplotlib/src/tikzplotlib/_save.py

Line 33 in 450712b

extra_groupstyle_parameters: dict = {},

it is dict.