Bump ReportGenerator from 4.8.4 to 4.8.6 (#530)

Author: dependabot[bot]

Directory.Build.targets

@@ -13,7 +13,7 @@
   <ItemGroup>
     <PackageReference Update="GitVersion.Tool" Version="5.6.6" />
     <PackageReference Update="JetBrains.ReSharper.CommandLineTools" Version="2020.3.2" />
-    <PackageReference Update="ReportGenerator" Version="4.8.4" />
+    <PackageReference Update="ReportGenerator" Version="4.8.6" />
     <PackageReference Update="Rocket.Surgery.Nuke" Version="0.14.3" />
   </ItemGroup>
   <ItemGroup>