remove reference to two_d_plots

tests/test_plots.py

@@ -13,7 +13,6 @@ from scientific_plots.types_ import Vector
 from scientific_plots.plot_settings import read_data_plot
 from scientific_plots.default_plots import (
     plot, two_plots, two_axis_plots, plot_surface)
-from scientific_plots import two_d_plot
 
 
 @mark.use_style