Bump MSTest.TestAdapter from 2.2.8 to 3.6.4

Bumps [MSTest.TestAdapter](https://github.com/microsoft/testfx) from 2.2.8 to 3.6.4.
- [Release notes](https://github.com/microsoft/testfx/releases)
- [Changelog](https://github.com/microsoft/testfx/blob/main/docs/Changelog.md)
- [Commits](microsoft/testfx@v2.2.8...v3.6.4)

---
updated-dependencies:
- dependency-name: MSTest.TestAdapter
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

build/Settings.Test.targets

@@ -18,7 +18,7 @@
   </ItemGroup>
 
   <ItemGroup Condition="'$(TsuTestingLib)' == 'MSTest'">
-    <PackageReference Include="MSTest.TestAdapter" Version="2.2.8" />
+    <PackageReference Include="MSTest.TestAdapter" Version="3.6.4" />
     <PackageReference Include="MSTest.TestFramework" Version="2.2.8" />
   </ItemGroup>