Triple-quoted strings do not ignore backslash before closing sequence

[Vampire]

If you look at https://github.com/Vampire/setup-wsl/blob/4eea7c92d6c56a39bfcebcdcb93be63388497f59/.github/workflows/test.main.kts#L385, from line 386 on the highlighting is broken because of the String end token not being recognized due to the backslash that should be ignored.