Bump ReportGenerator from 4.8.7 to 4.8.8 (#570)

Bumps [ReportGenerator](https://github.com/danielpalme/ReportGenerator) from 4.8.7 to 4.8.8.
- [Release notes](https://github.com/danielpalme/ReportGenerator/releases)
- [Commits](danielpalme/ReportGenerator@v4.8.7...v4.8.8)

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

Directory.Build.targets

@@ -13,7 +13,7 @@
     <ItemGroup>
         <PackageReference Update="GitVersion.Tool" Version="5.6.8"/>
         <PackageReference Update="JetBrains.ReSharper.CommandLineTools" Version="2021.1.2"/>
-        <PackageReference Update="ReportGenerator" Version="4.8.7"/>
+        <PackageReference Update="ReportGenerator" Version="4.8.8"/>
         <PackageReference Update="Rocket.Surgery.Nuke" Version="0.14.3"/>
     </ItemGroup>
     <ItemGroup>