Fix ContentType parsing in HttpClient utils
Update ServiceStack.Text.Tests.csproj
Upgrade to v15.4.0
bump to v5.13.2
Add JSV tests for new DateOnly TimeOnly .NET 6 types
bump to v5.12
bump to v5.11
bump to v5.10.4
Update Env.cs
Extract .NET 4.5 HttpUtils + add async overloads