This project was probably never intended to live as long as it did (as pointed out by the creator), but having a license is generally a good idea if people are contributing.
choosealicense.com is a pretty good resource for choosing a license.
TLDR:
If you don't really care what people do with the project -> MIT License
If you want the project to always be open source and only allow people to use the project in other open source projects -> GPLv3
This project was probably never intended to live as long as it did (as pointed out by the creator), but having a license is generally a good idea if people are contributing.
choosealicense.com is a pretty good resource for choosing a license.
TLDR:
If you don't really care what people do with the project -> MIT License
If you want the project to always be open source and only allow people to use the project in other open source projects -> GPLv3