Bump SixLabors.ImageSharp from 1.0.0-beta0007 to 3.1.3 in /tests/StbImageSharp.Testing#5

dependabot[bot] wants to merge 1 commit intomasterStbSharp/SafeStbImageSharp:masterfrom

dependabot/nuget/tests/StbImageSharp.Testing/SixLabors.ImageSharp-3.1.3StbSharp/SafeStbImageSharp:dependabot/nuget/tests/StbImageSharp.Testing/SixLabors.ImageSharp-3.1.3Copy head branch name to clipboard