Starscream said that you just need to find which GIT revision was tagged as 3.0. If you find that GIT hash, then you can compile it like any other dolphin build.
OS: Windows 10 64 bit Professional
CPU: AMD Ryzen 5900X
RAM: 48GB
GPU: Radeon 7800 XT
CPU: AMD Ryzen 5900X
RAM: 48GB
GPU: Radeon 7800 XT