Set lang version

Merge pull request #2896 from SixLabors/af/fix-3.1-build

[3.1] Set LangVersion=12 unconditionally

Merge pull request #2828 from SixLabors/js/issue-2806

Rewrite ChunkedMemoryStream

Merge pull request #2775 from SixLabors/js-fix-2771

Fix filtering on PNG encode.

Merge pull request #2770 from SixLabors/af/backport-2759-2.1.x

Backport 2759 to 2.1.x

Merge pull request #2716 from SixLabors/js/clear-buffers

Clear Pixel Buffers on Decode.

Merge pull request #2715 from SixLabors/backport/v2-memlimit

V2 - Limit all memory allocations in the MemoryAllocator layer

Merge pull request #2688 from SixLabors/js/backport-2681

Backport 2681

Allow nightlies from previous releases

Merge pull request #2637 from SixLabors/backport/webp-milliseconds

Backport: Fix WebP animation speed bug