tests: fixed remaining failing test
tests: fixed remaining failing test

the `Sequence` type does not refine `string`, so it prints `{}` as defined
in `List`. If we want to change that then fine, but the test was currently
wrong

unratito/ceylon.language,unratito/ceylon.language,jvasileff/ceylon.language,lucaswerkmeister/ceylon.language,ceylon/ceylon.language,lucaswerkmeister/ceylon.language,ceylon/ceylon.language,jvasileff/ceylon.language