BatchNorm is no longer experimental

[stepp1]

Hi everyone!

I installed the latest EqxVision and got an import error when importing equinox.experimental. This seems to be because Equinox graduated BatchNorm to stable on v0.10.3.

I'll create a short PR for this.

[lowlorenz]

Until this is fixed, downgrading equinox is an option.
pip install equinox==0.10.2