Bump Microsoft.NET.Test.Sdk from 18.5.1 to 18.6.0

---
updated-dependencies:
- dependency-name: Microsoft.NET.Test.Sdk
  dependency-version: 18.6.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

src/Directory.Packages.props

@@ -13,7 +13,7 @@
     <PackageVersion Include="Microsoft.EntityFrameworkCore.SqlServer" Version="10.0.8" />
     <PackageVersion Include="Npgsql" Version="10.0.2" />
     <PackageVersion Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="10.0.1" />
-    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.5.1" />
+    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.6.0" />
     <PackageVersion Include="NUnit" Version="4.6.1" />
     <PackageVersion Include="NUnit3TestAdapter" Version="6.2.0" />
     <PackageVersion Include="coverlet.collector" Version="10.0.1" />