Bump Microsoft.NET.Test.Sdk from 16.8.3 to 16.9.1 (#9)

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)

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

MimeTypes.Tests/MimeTypes.Tests.csproj

@@ -13,7 +13,7 @@
     <ItemGroup>
         <PackageReference Include="nunit" Version="3.13.1" />
         <PackageReference Include="NUnit3TestAdapter" Version="3.17.0" />
-        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.8.3" />
+        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.9.1" />
     </ItemGroup>
 
     <ItemGroup>