test: mark grid voronoi tests with intermittent tkinter/tcl errors as flaky (see JuliaGraphics/Tk.jl#67, pypa/virtualenv#93, pypa/virtualenv#627)

Author: wpbonelli

autotest/test_grid.py

@@ -901,6 +901,7 @@ def test_voronoi_grid(tmpdir, grid_info):
     assert len(ninvalid_cells) == 0, errmsg
 
 
+@flaky
 def test_voronoi_grid3(tmpdir):
     name = "vor3"
     answer_ncpl = 300
@@ -949,6 +950,7 @@ def test_voronoi_grid3(tmpdir):
     assert len(ninvalid_cells) == 0, errmsg
 
 
+@flaky
 def test_voronoi_grid4(tmpdir):
     name = "vor4"
     answer_ncpl = 410
@@ -988,6 +990,7 @@ def test_voronoi_grid4(tmpdir):
     assert len(ninvalid_cells) == 0, errmsg
 
 
+@flaky
 def test_voronoi_grid5(tmpdir):
     name = "vor5"
     answer_ncpl = 1305