Bump Microsoft.NET.Test.Sdk from 16.8.3 to 16.9.1 in /src

Bumps [Microsoft.NET.Test.Sdk](https://github.com/microsoft/vstest) from 16.8.3 to 16.9.1.
- [Release notes](https://github.com/microsoft/vstest/releases)
- [Commits](microsoft/vstest@v16.8.3...v16.9.1)

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

Author: dependabot-preview[bot]

src/Cake.AzureDevOps.Tests/Cake.AzureDevOps.Tests.csproj

@@ -14,7 +14,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.8.3" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.9.1" />
     <PackageReference Include="Cake.Core" Version="1.0.0" />
     <PackageReference Include="Cake.Testing" Version="1.0.0" />
     <PackageReference Include="Microsoft.TeamFoundationServer.Client" Version="16.143.2" />