Bump MSTest from 3.2.0 to 3.2.1 in /src

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] <[email protected]>

src/Bootstrap.Tests/Bootstrap.Tests.csproj

@@ -7,7 +7,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="MSTest" Version="3.2.0" />
+    <PackageReference Include="MSTest" Version="3.2.1" />
     <PackageReference Include="Reqnroll.MsTest" Version="1.0.0" />
   </ItemGroup>