chore(deps): update mstest monorepo to 3.9.3 (#26)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

src/Directory.Packages.props

@@ -15,8 +15,8 @@
         <PackageVersion Include="NUnit" Version="4.2.2" />
 
         <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
-        <PackageVersion Include="MSTest.TestAdapter" Version="3.6.0" />
-        <PackageVersion Include="MSTest.TestFramework" Version="3.6.0" />
+        <PackageVersion Include="MSTest.TestAdapter" Version="3.9.3" />
+        <PackageVersion Include="MSTest.TestFramework" Version="3.9.3" />
 
         <PackageVersion Include="xunit.assert" Version="2.9.3" />
         <PackageVersion Include="xunit" Version="2.9.3" />