fix: Check for usage string without assuming no ANSI colors

Author: effigies

nibabel/cmdline/tests/test_roi.py

@@ -141,7 +141,7 @@ def test_entrypoint(capsys):
         with pytest.raises(SystemExit):
             main()
     captured = capsys.readouterr()
-    assert captured.out.startswith('usage: nib-roi')
+    assert 'usage: nib-roi' in captured.out
 
 
 def test_nib_roi_unknown_axes(capsys):