Move from github.com/disintegration/gift to github.com/gohugoio/gift

Move from github.com/disintegration/gift to github.com/gohugoio/gift

With some performance improvements upstream, there's improvements in memory usage. Note that the benchmark below is full site builds with image processing:

```
goos: darwin
goarch: arm64
pkg: github.com/gohugoio/hugo/resources/images
cpu: Apple M1 Pro
               │ benchcmp.bench │  feat-forkgift-14397.bench   │
               │     sec/op     │   sec/op     vs base         │
ImageResize-10      74.60m ± 4%   73.75m ± 4%  ~ (p=0.093 n=6)

               │ benchcmp.bench │     feat-forkgift-14397.bench      │
               │      B/op      │     B/op      vs base              │
ImageResize-10     32.38Mi ± 1%   29.31Mi ± 1%  -9.49% (p=0.002 n=6)

               │ benchcmp.bench │     feat-forkgift-14397.bench     │
               │   allocs/op    │  allocs/op   vs base              │
ImageResize-10      12.53k ± 1%   12.05k ± 1%  -3.82% (p=0.002 n=6)
```

Closes #14397