Simplify test to use Image.new instead of opening file

Author: veeceey

Tests/test_imageops.py

@@ -258,9 +258,9 @@ def test_expand_palette(border: int | tuple[int, int, int, int]) -> None:
 
 @pytest.mark.parametrize("border", ((1,), (1, 2, 3), (1, 2, 3, 4, 5)))
 def test_expand_invalid_border(border: tuple[int, ...]) -> None:
-    with Image.open("Tests/images/hopper.ppm") as im:
-        with pytest.raises(ValueError):
-            ImageOps.expand(im, border)
+    im = Image.new("1", (1, 1))
+    with pytest.raises(ValueError):
+        ImageOps.expand(im, border)
 
 
 def test_colorize_2color() -> None: