Support animated Webp

[ycycxz]

log

hugo v0.83.1-5AFE0A57+extended windows/amd64 BuildDate=2021-05-02T14:38:05Z VendorInfo=gohugoio

[Static Webp] works very well, but Animated Webp:

<.Resize>: error calling Resize: 
image "C:\\Users\\username\\OneDrive\\Documents\\GitHub\\1\\assets\\3\\1.webp": 
resize \3\1.webp: webp: invalid format