Bump Microsoft.NET.Test.Sdk from 16.8.0 to 16.8.3 (#726)

Bumps [Microsoft.NET.Test.Sdk](https://github.com/microsoft/vstest) from 16.8.0 to 16.8.3.
- [Release notes](https://github.com/microsoft/vstest/releases)
- [Commits](https://github.com/microsoft/vstest/compare/v16.8.0...v16.8.3)

Signed-off-by: dependabot[bot] <[email protected]>

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

src/WinSW.Tests/WinSW.Tests.csproj

@@ -12,7 +12,7 @@
     </PackageReference>
     <PackageReference Include="Microsoft.Diagnostics.Runtime" Version="2.0.156101" />
     <PackageReference Include="Microsoft.Diagnostics.Runtime.Utilities" Version="2.0.0-rc.20303.3" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.8.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.8.3" />
     <PackageReference Include="xunit" Version="2.4.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.3">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>