add LAION 2B only training

[Soonhwan-Kwon]

add LAION 2B only training related to the issue below
#137

[Soonhwan-Kwon]

it is strange when I run psf/black on my machine, it outputs

python -m black open_flamingo/
reformatted /data4/open_flamingo/open_flamingo/train/train_utils.py

All done! ✨ 🍰 ✨
1 file reformatted, 19 files left unchanged.

[anas-awadalla]

Can you upgrade black? I remember I ran into this problem earlier and that was the fix. If not no worries! Thanks for putting this together. I will take a look and merge :)

[anas-awadalla]

Thanks for putting this together. I think we should first clean up the duplicate code in train_utils.py before merging.

[Soonhwan-Kwon]

I committed updates last week, and I tested run for laion dataset. Please let me know if there are more feedbacks.

[anas-awadalla]

Thanks @Soonhwan-Kwon! We will merge this but may take a few days for me to do so.