OpenSTA is dual licensed. It is released under GPL v3 as OpenSTA and is also licensed for commerical applications by Parallax Software without the GPL's requirements.
For this to be possible you need to require your contributors to sign a CLA with Parallax Software. However, I don't see anything in your README about this?
You README.md says;
For this to be possible you need to require your contributors to sign a CLA with Parallax Software. However, I don't see anything in your README about this?
You can find out more information about CLAs at https://opensource.google.com/docs/cla/