chore: Bump the testing group with 1 update

Bumps Microsoft.NET.Test.Sdk from 18.5.1 to 18.7.0

---
updated-dependencies:
- dependency-name: Microsoft.NET.Test.Sdk
  dependency-version: 18.7.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: testing
...

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

Author: dependabot[bot]

tests/Directory.Build.props

@@ -21,7 +21,7 @@
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.5.1" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.7.0" />
     <PackageReference Include="NUnit" Version="4.6.1" />
     <PackageReference Include="NUnit3TestAdapter" Version="6.2.0" />
     <PackageReference Include="Shouldly" Version="4.3.0" />