Bump MessagePack from 2.5.140 to 2.5.168

Bumps [MessagePack](https://github.com/MessagePack-CSharp/MessagePack-CSharp) from 2.5.140 to 2.5.168.
- [Release notes](https://github.com/MessagePack-CSharp/MessagePack-CSharp/releases)
- [Changelog](https://github.com/MessagePack-CSharp/MessagePack-CSharp/blob/master/prepare_release.ps1)
- [Commits](https://github.com/MessagePack-CSharp/MessagePack-CSharp/commits)

---
updated-dependencies:
- dependency-name: MessagePack
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

src/Backgrounder.Azure.ServiceBus/Backgrounder.Azure.ServiceBus.csproj

@@ -6,7 +6,7 @@
 
   <ItemGroup>
     <PackageReference Include="Azure.Messaging.ServiceBus" Version="7.17.5" />
-    <PackageReference Include="MessagePack" Version="2.5.140" />
+    <PackageReference Include="MessagePack" Version="2.5.168" />
     <PackageReference Include="Microsoft.Extensions.Hosting.Abstractions" Version="8.0.0" />
     <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="8.0.1" />
     <PackageReference Include="Microsoft.Extensions.Options.ConfigurationExtensions" Version="8.0.0" />