fix: Bump MSTest.TestAdapter and MSTest.TestFramework

Bumps MSTest.TestAdapter from 4.1.0 to 4.2.1
Bumps MSTest.TestFramework from 4.1.0 to 4.2.1

---
updated-dependencies:
- dependency-name: MSTest.TestAdapter
  dependency-version: 4.2.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: MSTest.TestFramework
  dependency-version: 4.2.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

JWLMerge.Tests/JWLMerge.Tests.csproj

@@ -19,8 +19,8 @@
   </ItemGroup>
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.3.0" />
-    <PackageReference Include="MSTest.TestAdapter" Version="4.1.0" />
-    <PackageReference Include="MSTest.TestFramework" Version="4.1.0" />
+    <PackageReference Include="MSTest.TestAdapter" Version="4.2.1" />
+    <PackageReference Include="MSTest.TestFramework" Version="4.2.1" />
     <PackageReference Include="coverlet.collector" Version="8.0.1">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>