Simplify and relax dependencies (Take 2) (#818)

* Remove unused einops dependency

* Make Weights & Biases monitoring optional

- Move `wandb` to `./requirements/requirements-wandb.txt`
- Clean up `./deepy.py`
- Make GPT-NeoX not explode if `wandb` is not installed.
- Tell the user when `wandb` is not importable and explain how to fix.
- Remove implicit dependence on `shortuuid`.
- Ensure that `wandb` is installed in Dockerfile.

* Relax many dependencies

* Remove usage of uuid.uuid4()

* Update Dockerfile

Add flash attention install

* Update logging.py to pass when wandb is unimportable

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Co-authored-by: Quentin Anthony <[email protected]>

Merge pull request #813 from EleutherAI/fix-tok-import

fix unexpected indent error for conditional `tiktoken` import

Merge pull request #492 from EleutherAI/dependabot/pip/requirements/n…

…umpy-1.21.0

Bump numpy from 1.20.2 to 1.21.0 in /requirements