If you are actually practicing for a modern exam, training with 2013 materials might do more harm than good since exam formats, task numbering, and grading criteria have shifted significantly since then.
If you are stuck trying to check your work against this specific 2013 edition, tracking down exact digital keys is incredibly difficult due to the age of the files. Consider these more practical alternatives:
Most of Senina's Legio (Легион) prep books traditionally include an answer key at the very end of the manual for the practice tests.
Книга: ГИА-2013. Русский язык. 9 класс - Лабиринт