fix: CosineAnnealingLR is missing

[hoangtnm]

According to Moco_v2 paper, cosine lr scheduler is used but the lighting-bolts's implementation has not implemented it yet.

What does this PR do?

Add CosineAnnealingLR as the learning rate scheduler to follow Moco_v2 paper

Fixes # (issue)

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[ananyahjha93]

@hoangtnm thanks for the contribution

Also, we are now in the process of deprecating the bolts implementations of self-supervised learning models and directly support vissl integration in flash: https://lightning-flash.readthedocs.io/en/latest/reference/image_embedder.html

So, we won't be maintaining these implementations any further. You are welcome to contribute to our self-supervised learning vissl integration in flash.

[tchaton]

LGTM!