Bump MessagePack from 2.0.323 to 2.1.90 in /samples/XRPC.WPF/Client

Bumps [MessagePack](https://github.com/neuecc/MessagePack-CSharp) from 2.0.323 to 2.1.90.
- [Release notes](https://github.com/neuecc/MessagePack-CSharp/releases)
- [Commits](MessagePack-CSharp/MessagePack-CSharp@v2.0.323...v2.1.90)

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

samples/XRPC.WPF/Client/packages.config

@@ -2,7 +2,7 @@
 <packages>
   <package id="BeetleX" version="1.4.8" targetFramework="net472" />
   <package id="BeetleX.XRPC.Clients" version="0.8.2.3" targetFramework="net472" />
-  <package id="MessagePack" version="2.0.323" targetFramework="net472" />
+  <package id="MessagePack" version="2.1.90" targetFramework="net472" />
   <package id="MessagePack.Annotations" version="2.0.323" targetFramework="net472" />
   <package id="MessagePackAnalyzer" version="2.0.323" targetFramework="net472" />
   <package id="Newtonsoft.Json" version="12.0.3" targetFramework="net472" />