If you want to support Android, I'd highly recommend using LibGDX instead of SlickAE. SlickAE is pretty much discontinued/dead, really buggy, very limited, and is actually just a thin wrapper on top of LibGDX. Slick was never designed with Android or OpenGL ES in mind (i.e. touch, accelerometer, state management, native performance, etc) and so it's never going to work well without a complete overhaul of the library.
Slick currently uses the latest version of OpenGL?
Slick uses "old school" OpenGL techniques (immediate mode / fixed function), which still work on all modern computers. To reach a wider audience, it does not employ extensions or features from the latest versions of OpenGL (3.0+).
With that said, since Slick's dev branch uses the latest version of LWJGL, you are free to use any GL 3.0+ features in your Slick projects, at the cost of losing some users who don't support it.
Worth noting, these "old school" techniques do not work on OpenGL ES (mobile / embedded systems), which is why SlickAE has to rely on LibGDX for everything.