v0.0.3 release changes (FAIR-Chem#256)

* Changes for v0.0.3

* Reformatting MODELS.md

* GemNet scaling factors

* Env update

* Correct pytorch version in readme

* Update OCPCalc docs

* gemnet scaling factors file

* remove unused var

* remove redundant lines in collate fn

* Updates gitignore

Co-authored-by: Muhammed Shuaibi <[email protected]>

pointer to notebooks, arxiv v2 (FAIR-Chem#187)

* pointer to notebooks, arxiv v2

* Adds DimeNet++ to readme

Co-authored-by: Abhishek Das <[email protected]>

remove distributed flag (FAIR-Chem#86)