New Optimizer: Implement Adam-Mini optimizer

[SicariusSicariiStuff]

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🔖 Feature description

Paper:
https://arxiv.org/abs/2406.16793

TL;DR
Adam-mini should make it easier and faster to train models on home hardware.
In theory, it shouldn't be overly complicated to implement it, as it is very similar to AdamW

✔️ Solution

Implement Adam-Mini in Axolotl.

❓ Alternatives

Keep using AdamW

📝 Additional Context

Adam-mini should probably be 'sort-of' compatible with DeepSpeed right out of the box, greatly increasing training speed and reducing memory footprint.

Acknowledgements

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