Bump Microsoft.NET.Test.Sdk in /unit-tests/.dependabot (#940)

Bumps [Microsoft.NET.Test.Sdk](https://github.com/microsoft/vstest) from 17.0.0 to 17.1.0.
- [Release notes](https://github.com/microsoft/vstest/releases)
- [Commits](microsoft/vstest@v17.0.0...v17.1.0)

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

Signed-off-by: dependabot[bot] <support@github.com>

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

unit-tests/unit-tests.ghulproj

@@ -10,7 +10,7 @@
     <PackageReference Include="ghul.pipes" />
     <PackageReference Include="ghul.runtime" />
 
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.0.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.1.0" />
     <PackageReference Include="Moq" Version="4.16.1" />
     <PackageReference Include="MSTest.TestAdapter" Version="2.2.8" />
     <PackageReference Include="MSTest.TestFramework" Version="2.2.8" />