Bump Microsoft.NET.Test.Sdk from 17.12.0 to 18.4.0#6

dependabot[bot] wants to merge 1 commit intomainStefanTheCode/PragmaticDotNetCodeRules:mainfrom

dependabot/nuget/tests/PragmaticDotNetCodeRules.ArchTests/Microsoft.NET.Test.Sdk-18.4.0StefanTheCode/PragmaticDotNetCodeRules:dependabot/nuget/tests/PragmaticDotNetCodeRules.ArchTests/Microsoft.NET.Test.Sdk-18.4.0Copy head branch name to clipboard