@Thalia - as theducks suggested you are out of luck.
If I tried really hard there is a remote possibility I could dig up an old backup, or you might find another user on here who still has it. However as the Goodreads website has changed several times since then and I have zero interest in maintaining multiple versions of this plugin it wouldn't matter anyway.
I would have thought the huge list of calibre improvements/fixes and plugins would be reason enough for sorting out a new machine