Bump Newtonsoft.Json and Microsoft.NET.Test.Sdk (#231)

Bumps [Newtonsoft.Json](https://github.com/JamesNK/Newtonsoft.Json) and [Microsoft.NET.Test.Sdk](https://github.com/microsoft/vstest). These dependencies needed to be updated together.

Updates `Newtonsoft.Json` from 13.0.3 to 13.0.1
- [Release notes](https://github.com/JamesNK/Newtonsoft.Json/releases)
- [Commits](JamesNK/Newtonsoft.Json@13.0.3...13.0.1)

Updates `Microsoft.NET.Test.Sdk` from 17.11.1 to 17.12.0
- [Release notes](https://github.com/microsoft/vstest/releases)
- [Changelog](https://github.com/microsoft/vstest/blob/main/docs/releases.md)
- [Commits](microsoft/vstest@v17.11.1...v17.12.0)

---
updated-dependencies:
- dependency-name: Newtonsoft.Json
  dependency-type: direct:production
  update-type: version-update:semver-patch
- 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>

Author: dependabot[bot]

test/Serilog.Sinks.Splunk.TCP.Tests/Serilog.Sinks.Splunk.TCP.Tests.csproj

@@ -9,7 +9,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.11.1" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
     <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
     <PackageReference Include="xunit" Version="2.9.2" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2">

test/Serilog.Sinks.Splunk.Tests/Serilog.Sinks.Splunk.Tests.csproj

@@ -8,7 +8,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.11.1" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
     <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
     <PackageReference Include="xunit" Version="2.9.2" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2">