Bump ReportGenerator from 4.5.2 to 4.6.4

Bumps [ReportGenerator](https://github.com/danielpalme/ReportGenerator) from 4.5.2 to 4.6.4.
- [Release notes](https://github.com/danielpalme/ReportGenerator/releases)
- [Commits](danielpalme/ReportGenerator@v4.5.2...v4.6.4)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

Directory.Build.targets

@@ -11,7 +11,7 @@
     <ItemGroup>
         <PackageReference Update="GitVersion.Tool" Version="5.3.7" />
         <PackageReference Update="JetBrains.ReSharper.CommandLineTools" Version="2019.3.4" />
-        <PackageReference Update="ReportGenerator" Version="4.5.2" />
+        <PackageReference Update="ReportGenerator" Version="4.6.4" />
         <PackageReference Update="Rocket.Surgery.Nuke" Version="0.14.0-beta.9" />
     </ItemGroup>
     <ItemGroup>