The latest version of software for the GoPiGo-3 is GoPiGo O/S 3.0.2 which you can download from here:
Raspbian for Robots has been depreciated.
You can use either GoPiGo O/S, (which is a mixture of Raspbian for Robots and Dexter O/S, and includes all the learning tools), or you can download the “legacy” Buster release of Raspbian and install the GoPiGo libraries over it if you don’t need Bloxter.
If you are doing more advanced programming, and don’t want the lower-level educational stuff, do the Raspbian Legacy and download the GoPiGo stuff over it.
I don’t remember the exact link for the GoPiGo libraries, but if you search the forms for “curl”, you should find it. You can also search for “legacy Raspbian” and that should lead you to instructions how to install the GoPiGo libraries.