Update dependency ReportGenerator to 5.3.9

Author: renovate[bot]

algorithm_exercises_csharp_test/algorithm_exercises_csharp_test.csproj

@@ -38,7 +38,7 @@
     <PackageReference Include="MSTest.TestAdapter" Version="3.5.2" />
     <PackageReference Include="MSTest.TestFramework" Version="3.5.2" />
     <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
-    <PackageReference Include="ReportGenerator" Version="5.3.8" />
+    <PackageReference Include="ReportGenerator" Version="5.3.9" />
   </ItemGroup>
 
   <!-- Exclude test project from coverage -->