Bump MessagePack from 2.0.323 to 2.1.90 in /src

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>

src/BeetleX.XRPC.csproj

@@ -27,7 +27,7 @@
   <ItemGroup>
     <PackageReference Include="BeetleX" Version="1.5.4" />
     <PackageReference Include="EventNext" Version="0.9.8" />
-    <PackageReference Include="MessagePack" Version="2.0.323" />
+    <PackageReference Include="MessagePack" Version="2.1.90" />
     <PackageReference Include="Newtonsoft.Json" Version="12.0.3" />
   </ItemGroup>