chore(deps): update dependency mstest.testframework to 4.2.1

Author: renovate[bot]

Directory.Packages.props

@@ -19,7 +19,7 @@
     <PackageVersion Include="Microsoft.Testing.Extensions.CodeCoverage" Version="18.5.2" />
     <PackageVersion Include="Microsoft.TestPlatform.TestHost" Version="18.4.0" />
     <PackageVersion Include="MSTest.TestAdapter" Version="4.1.0" />
-    <PackageVersion Include="MSTest.TestFramework" Version="4.1.0" />
+    <PackageVersion Include="MSTest.TestFramework" Version="4.2.1" />
     <PackageVersion Include="NUnit" Version="4.5.1" />
     <PackageVersion Include="NUnit3TestAdapter" Version="6.2.0" />
     <PackageVersion Include="NUnit.Analyzers" Version="4.12.0" />