Bump MSTest.TestFramework in /FeatureFlags/FeatureFlags.Tests

Bumps [MSTest.TestFramework](https://github.com/microsoft/testfx) from 2.2.6 to 2.2.7.
- [Release notes](https://github.com/microsoft/testfx/releases)
- [Commits](microsoft/testfx@v2.2.6...v2.2.7)

---
updated-dependencies:
- dependency-name: MSTest.TestFramework
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

FeatureFlags/FeatureFlags.Tests/FeatureFlags.Tests.csproj

@@ -34,7 +34,7 @@
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.11.0" />
     <PackageReference Include="Moq" Version="4.16.1" />
     <PackageReference Include="MSTest.TestAdapter" Version="2.2.6" />
-    <PackageReference Include="MSTest.TestFramework" Version="2.2.6" />
+    <PackageReference Include="MSTest.TestFramework" Version="2.2.7" />
   </ItemGroup>
 
   <ItemGroup>