Bump MSTest from 3.2.0 to 3.2.1

Bumps [MSTest](https://github.com/microsoft/testfx) from 3.2.0 to 3.2.1.
- [Release notes](https://github.com/microsoft/testfx/releases)
- [Changelog](https://github.com/microsoft/testfx/blob/main/docs/Changelog.md)
- [Commits](microsoft/testfx@v.3.2.0...v3.2.1)

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

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

src/Sep.Test/Sep.Test.csproj

@@ -22,7 +22,7 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
     <PackageReference Include="PublicApiGenerator" Version="11.1.0" />
-    <PackageReference Include="MSTest" Version="3.2.0" />
+    <PackageReference Include="MSTest" Version="3.2.1" />
   </ItemGroup>
 
 </Project>