reduce tolerance for inset plot comparison

Author: josesho

dabest/tests/test_03_plotting.py

@@ -114,7 +114,7 @@ def test_10_cummings_multi_groups():
 
 
 @pytest.mark.mpl_image_compare
-def test_11_inset_plots():
+def test_11_inset_plots(tolerance=8):
 
     # Load the iris dataset. Requires internet access.
     iris = pd.read_csv("https://github.com/mwaskom/seaborn-data/raw/master/iris.csv")