Upgrade to Cog version 0.1 - pydantic

[chenxwh]

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The new version of Cog improves the Python API, along with several other changes. Particularly pydantic is now used for Predictor and the previous version will be deprecated.

This PR upgrades the Replicate demo and API to Cog version >= 0.1. I have already pushed this to Replicate, so you don't need to do anything for the demo to keep working :) https://replicate.com/jingyunliang/swinir