Though given the amount of hassle doing that entails,
another option is to not redistribute code released under the GPL and just stick to the more forgiving licences. :P
Assuming the source is being taken from GitHub repos,
the licence files should already be provided with the source code in most cases.
Some people might specify the licence as part of the source code but not provide a licence file.
If the licence isn’t part of the source code and there’s no licence file then technically you probably aren’t allowed to redistribute the game or the code.