Open flickrss.php, look for line 178, which looks like this:
preg_match('<http://farm[0-9]{0,3}\.static.flickr\.com/\d+?\/([^.]*)
\.jpg>', $img_to_cache, $flickrSlugMatches);
Change it to this:
preg_match('<http://farm[0-9]{0,3}\.static.?flickr\.com/\d+?\/([^.]*)
\.jpg>', $img_to_cache, $flickrSlugMatches);
And that's it. Should be working again. Hope this helps.
Only update plugin with new version.