Bump SixLabors.ImageSharp from 2.1.3 to 2.1.8 in /src/ImageResizerFunction#4

dependabot[bot] wants to merge 1 commit intomainstevetemple/Image-Resizer-Azure-Function:mainfrom

dependabot/nuget/src/ImageResizerFunction/SixLabors.ImageSharp-2.1.8stevetemple/Image-Resizer-Azure-Function:dependabot/nuget/src/ImageResizerFunction/SixLabors.ImageSharp-2.1.8Copy head branch name to clipboard