fix import error

tests/tests_pytest/plot.py

@@ -25,7 +25,7 @@ matplotlib.rcParams['font.family'] = 'Times New Roman'
 matplotlib.rcParams['mathtext.default'] = 'regular'
 import matplotlib.pyplot as plt
 import matplotlib.patches as mpatches
-from ticks_and_grid import ticks_and_grid
+from tests.tests_pytest.ticks_and_grid import ticks_and_grid
 
 
 # Function to compute standard deviation that is not strongly affected by outliers