Try setting Agg backend for Matplotlib testing

skimage/io/tests/test_mpl_imshow.py

@@ -1,16 +1,22 @@
 import numpy as np
+import matplotlib
 import pytest
 
 from skimage import io
 from skimage._shared._warnings import expected_warnings
 from skimage._shared._dependency_checks import is_wasm
 
+import os
+
 plt = pytest.importorskip("matplotlib.pyplot")
 
 
 def setup():
     io.reset_plugins()
 
+os.environ["MPLBACKEND"] = "agg"
+matplotlib.use('Agg')
+
 
 # test images. Note that they don't have their full range for their dtype,
 # but we still expect the display range to equal the full dtype range.