Bump the dotnet group (#45422)

Bumps the dotnet group in /samples/snippets/core/testing/unit-testing-vb-mstest/vb with 2 updates: [MSTest.TestAdapter](https://github.com/microsoft/testfx) and [MSTest.TestFramework](https://github.com/microsoft/testfx).


Updates `MSTest.TestAdapter` from 3.8.2 to 3.8.3
- [Release notes](https://github.com/microsoft/testfx/releases)
- [Changelog](https://github.com/microsoft/testfx/blob/main/docs/Changelog.md)
- [Commits](microsoft/testfx@v3.8.2...v3.8.3)

Updates `MSTest.TestFramework` from 3.8.2 to 3.8.3
- [Release notes](https://github.com/microsoft/testfx/releases)
- [Changelog](https://github.com/microsoft/testfx/blob/main/docs/Changelog.md)
- [Commits](microsoft/testfx@v3.8.2...v3.8.3)

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

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

Author: dependabot[bot]

samples/snippets/core/testing/unit-testing-vb-mstest/vb/PrimeService.Tests/PrimeService.Tests.vbproj

@@ -8,8 +8,8 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.13.0" />
-    <PackageReference Include="MSTest.TestAdapter" Version="3.8.2" />
-    <PackageReference Include="MSTest.TestFramework" Version="3.8.2" />
+    <PackageReference Include="MSTest.TestAdapter" Version="3.8.3" />
+    <PackageReference Include="MSTest.TestFramework" Version="3.8.3" />
   </ItemGroup>
 
   <ItemGroup>