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]

test/SimpleAPI.Tests/SimpleAPI.Tests.csproj

@@ -20,7 +20,7 @@
     <PackageReference Include="Amazon.Lambda.TestUtilities" Version="4.1.0" />
     <PackageReference Include="Amazon.Lambda.APIGatewayEvents" Version="3.0.0" />
     <PackageReference Include="AWSSDK.Extensions.NETCore.Setup" Version="4.0.4.1" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.5.1" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.6.0" />
     <PackageReference Include="xunit" Version="2.9.3" />
     <PackageReference Include="xunit.runner.visualstudio" Version="3.1.5" />
   </ItemGroup>