Bump NuGet.Build.Tasks.Pack from 6.8.0 to 6.9.1

Bumps [NuGet.Build.Tasks.Pack](https://github.com/NuGet/NuGet.Client) from 6.8.0 to 6.9.1.
- [Release notes](https://github.com/NuGet/NuGet.Client/releases)
- [Commits](https://github.com/NuGet/NuGet.Client/commits)

---
updated-dependencies:
- dependency-name: NuGet.Build.Tasks.Pack
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

FluentRandomPicker/FluentRandomPicker.csproj

@@ -70,7 +70,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="NuGet.Build.Tasks.Pack" Version="6.8.0"><IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    <PackageReference Include="NuGet.Build.Tasks.Pack" Version="6.9.1"><IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>
     <PackageReference Include="StyleCop.Analyzers" Version="1.2.0-beta.556">