Keep date-like strings as strings when deserializing - #261

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4, actions/setup-dotnet@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

/home/runner/work/SlackNet/SlackNet/SlackNet/WebApi/ChatApi.cs(107,127): warning CS1574: XML comment has cref attribute 'unfurls' that could not be resolved [/home/runner/work/SlackNet/SlackNet/SlackNet/SlackNet.csproj::TargetFramework=netstandard2.0]

/home/runner/work/SlackNet/SlackNet/SlackNet/WebApi/ChatApi.cs(79,176): warning CS1574: XML comment has cref attribute 'metadata' that could not be resolved [/home/runner/work/SlackNet/SlackNet/SlackNet/SlackNet.csproj::TargetFramework=netstandard2.0]

/home/runner/work/SlackNet/SlackNet/SlackNet/WebApi/ChatApi.cs(79,151): warning CS1574: XML comment has cref attribute 'unfurls' that could not be resolved [/home/runner/work/SlackNet/SlackNet/SlackNet/SlackNet.csproj::TargetFramework=netstandard2.0]

/home/runner/work/SlackNet/SlackNet/SlackNet/WebApi/ChatApi.cs(74,152): warning CS1574: XML comment has cref attribute 'metadata' that could not be resolved [/home/runner/work/SlackNet/SlackNet/SlackNet/SlackNet.csproj::TargetFramework=netstandard2.0]

/home/runner/work/SlackNet/SlackNet/SlackNet/WebApi/ChatApi.cs(74,127): warning CS1574: XML comment has cref attribute 'unfurls' that could not be resolved [/home/runner/work/SlackNet/SlackNet/SlackNet/SlackNet.csproj::TargetFramework=netstandard2.0]

/home/runner/work/SlackNet/SlackNet/SlackNet/WebApi/CanvasesApi.cs(64,107): warning CS1574: XML comment has cref attribute 'channelIds' that could not be resolved [/home/runner/work/SlackNet/SlackNet/SlackNet/SlackNet.csproj::TargetFramework=netstandard2.0]

/home/runner/work/SlackNet/SlackNet/SlackNet/WebApi/CanvasesApi.cs(63,113): warning CS1574: XML comment has cref attribute 'userIds' that could not be resolved [/home/runner/work/SlackNet/SlackNet/SlackNet/SlackNet.csproj::TargetFramework=netstandard2.0]

/home/runner/work/SlackNet/SlackNet/SlackNet/WebApi/CallsApi.cs(17,159): warning CS1574: XML comment has cref attribute 'createdByUserId' that could not be resolved [/home/runner/work/SlackNet/SlackNet/SlackNet/SlackNet.csproj::TargetFramework=netstandard2.0]

/home/runner/work/SlackNet/SlackNet/SlackNet/Objects/WorkObjects/EntityAttributes.cs(56,57): warning CS1574: XML comment has cref attribute 'DateUpdated' that could not be resolved [/home/runner/work/SlackNet/SlackNet/SlackNet/SlackNet.csproj::TargetFramework=netstandard2.0]

/home/runner/work/SlackNet/SlackNet/SlackNet/Objects/WorkObjects/EntityAttributes.cs(48,57): warning CS1574: XML comment has cref attribute 'DateUpdated' that could not be resolved [/home/runner/work/SlackNet/SlackNet/SlackNet/SlackNet.csproj::TargetFramework=netstandard2.0]