The results of teamwork are not solely yours, and you have to be mindful how you share them.
As Mefitico mentioned in their answer, you may not have the rights to use the code you offered to that project. It's important to note that "open source" or "on GitHub" doesn't mean "do whatever" (though there is a license for that too). For example, the popular MIT license includes the provision:
Permission is hereby granted, free of charge, to any person obtaining a copy of this software … to deal in the Software without restriction, including without limitation to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software …
— The MIT License (via Open Source Initiative)
If you were the sole copyright holder, that would be fine — you could offer such a license to your code, and the project could include your code in their code. But it's very likely you're not the only copyright holder:
- If this is group research, you may share copyright with your advisor.
- If you are a paid researcher (e.g., supported by a grant or research assistantship), there is probably a clause in your contract that grants a license to the university or institution, which may be in conflict with the license you would grant to this project.
- Your contract may even grant sole copyright of any results of your research to your university or the institution that funds your grant.
- If you want to publish your results, you may have to transfer copyright of your published material to the journal.
So as you can see, the results of your research really aren't yours to share freely (even if that feels like the goal of research). This is a very common issue for people who write software professionally. It's important to talk with your advisor about what you can and can't do with the results.
All that said, it's probably not going to be a big deal. Likely no one will care that some niche open source project has a few lines of code based on this research. But the road to hell is paved with good intentions, and it's easy to get into trouble if you don't pay attention to your licenses.