Apparently, they really didn't

The only wild ones left are of a small population in South China and when compared to fossils from Jurassic, it hasn't changed that much.

Although, I admit I dont know how reliable this good news network is, but, it says any variance we see today is due to [human intervention, as we pretty much saved them from extinction.

Looking at the wikipedia page makes me think it has kinda stopped evolving and has not changed much since the fossil age.

https://wikipedia.org/wiki/Ginkgo and more specifically https://wikipedia.org/wiki/Ginkgo_biloba

It is the last living species in the order Ginkgoales, which first appeared over 290 million years ago, and fossils very similar to the living species, belonging to the genus Ginkgo, extend back to the Middle Jurassic epoch approximately 170 million years ago.