Bump MessagePack in /src/Senparc.CO2NET.Cache.CsRedis.Tests

Bumps [MessagePack](https://github.com/MessagePack-CSharp/MessagePack-CSharp) from 2.5.171 to 2.5.187.
- [Release notes](https://github.com/MessagePack-CSharp/MessagePack-CSharp/releases)
- [Commits](MessagePack-CSharp/MessagePack-CSharp@v2.5.171...v2.5.187)

---
updated-dependencies:
- dependency-name: MessagePack
  dependency-version: 2.5.187
  dependency-type: direct:production
...

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

Author: dependabot[bot]

src/Senparc.CO2NET.Cache.CsRedis.Tests/Senparc.CO2NET.Cache.CsRedis.Tests.net8.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
 	  <TargetFramework>net8.0</TargetFramework>
@@ -19,7 +19,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="MessagePack" Version="2.5.171" />
+    <PackageReference Include="MessagePack" Version="2.5.187" />
     <PackageReference Include="MessagePackAnalyzer" Version="2.5.171">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>