Update README.md

[princepride]

The url of BLIP-Diffusion is wrong. I changed it to https://arxiv.org/abs/2305.14720

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[princepride]

I noticed that the link to the paper 'July 2023, released implementation of BLIP-Diffusion' still points to the wrong address. It should be changed to 'https://arxiv.org/abs/2305.14720'

https://github.com/salesforce/LAVIS/assets/29850264/3051f93b-49f6-4b45-8ded-2957091edf7c