The license information on GitHub says CC0. Your CurseForge claims that this is a port of Shadows-of-Fire/FastFurnace; if thatʼs true then you donʼt own the copyright to a lot of the code and you therefore canʼt give that up. CurseForge says you used the MIT license, which you can legally use; you should update the GitHub page to include that and to clarify which parts were written by Shadows-of-Fire and which were written by you.

Additionally, it would be nice if the README was about the actual mod and not the example project you used to make this from.