Fill in changelog and bump version for 0.25.3

[Shnatsel]

Let's get the work we did on image orientation into the hands of users!

[fintelia]

The one thing I've been second guessing is whether Orientation should be a top-level type. I've been wanting to reduce the number of top level types, and we probably will be adding a metadata module to group all the other metadata related types we add, so I think we it might be good to place Orientation there to start with

[Shnatsel]

I've opened #2349 to relocate Orientation

[Shnatsel]

I've rewritten the changelog entry for rayon. I don't think we should wait on the exr change to ship this, since it appears to be a breaking change, the maintainer is busy, and so there is no clear timeline for it.

[HeroicKatora]

@fintelia If you agree with preparing 0.26 next, feel free to merge #2344 after the merge of the tagged release commit.

[fintelia]

@HeroicKatora Sorry I've been meaning to respond in that other thread. I wrote up some thoughts here, but rather than working on 0.26, I actually think that we should old off starting a major release for a little bit and then make a 1.0 release.

[fintelia]

Might be worth adding that this release brings substantially improved lossless WebP decoding performance. I measured it being between 2x and 2.5x faster!

(We usually don't mention codec improvements because they tend not to be tied to image releases, but these specific optimizations were bundled with the image-webp 0.2.0 release)

[Shnatsel]

The changelog still mentions #2348 which hasn't landed yet. So please don't publish a release just yet!

I'm hoping we could merge kornelski/cavif-rs#85 soon and fix the whole issue around MSRV. If it's not merged in a couple of days, we can pin an older ravif and then ship.

[Shnatsel]

Ah, nevermind, too late 😅

I've opened #2352 to amend the changelog.