Bump Microsoft.NET.Test.Sdk from 18.7.0 to 18.8.1 (#209)

---
updated-dependencies:
- dependency-name: Microsoft.NET.Test.Sdk
  dependency-version: 18.8.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

FolderDiffIL4DotNet.Tests/FolderDiffIL4DotNet.Tests.csproj

@@ -20,7 +20,7 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.7.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.8.1" />
     <PackageReference Include="FsCheck.Xunit" Version="2.16.6" />
     <PackageReference Include="xunit" Version="2.9.3" />
     <PackageReference Include="Xunit.SkippableFact" Version="1.5.61" />