Adding support for Gemma4 model family

[sharonyu-115]

Add the RL support for Gemma4 model family.

[zeel2104]

Is it open for contribution?

[sharonyu-115]

Is it open for contribution?

hi @zeel2104 thanks for your interest. I’m working on this and should be able to share my branch in a day or two. Once I do, you’re very welcome to take a look and contribute if you’d like.