Bump Microsoft.NET.Test.Sdk from 17.11.1 to 18.5.1 (#15)

---
updated-dependencies:
- dependency-name: Microsoft.NET.Test.Sdk
  dependency-version: 18.5.1
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

Directory.Packages.props

@@ -11,7 +11,7 @@
   <ItemGroup>
     <PackageVersion Include="xunit" Version="$(XunitVersion)" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="$(XunitRunnerVersion)" />
-    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.11.1" />
+    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.5.1" />
     <PackageVersion Include="coverlet.collector" Version="6.0.2" />
   </ItemGroup>
   <!-- SourceLink -->