[ci] fix octave error

Author: fangq

test/run_jsonlab_test.m

@@ -487,7 +487,7 @@ function run_jsonlab_test(tests)
     test_jsonlab('boolean false', @saveyaml, false, 'false', 'ParseLogical', 1);
     test_jsonlab('empty array', @saveyaml, [], '[]');
     test_jsonlab('empty cell', @saveyaml, {}, '[]');
-    test_jsonlab('simple string', @saveyaml, 'test', 'test');
+    test_jsonlab('simple string', @saveyaml, 'teststring', 'teststring');
     test_jsonlab('string with spaces', @saveyaml, 'hello world', '"hello world"');
 
     % Vectors and arrays