Bump MSTest.TestAdapter from 4.1.0 to 4.2.1 (#343)

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

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Author: dependabot[bot]

Directory.Packages.props

@@ -15,7 +15,7 @@
     <PackageVersion Include="Microsoft.SourceLink.GitHub" Version="10.0.202" PrivateAssets="All" />
     <PackageVersion Include="Microsoft.VisualStudio.Interop" Version="17.14.40260" />
     <PackageVersion Include="Microsoft.Windows.CsWin32" Version="0.3.275" />
-    <PackageVersion Include="MSTest.TestAdapter" Version="4.1.0" />
+    <PackageVersion Include="MSTest.TestAdapter" Version="4.2.1" />
     <PackageVersion Include="MSTest.TestFramework" Version="4.2.1" />
     <PackageVersion Include="System.CommandLine" Version="2.0.6" />
     <PackageVersion Include="System.Drawing.Common" Version="10.0.5" />