Remove JsonSerializerOptions copy in `ProblemDetailsJsonOptionsSetup`

[brunolins16]

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Is your feature request related to a problem? Please describe the problem.

JsonSerializerOptions.AddContext won't make the options read-only anymore (dotnet/runtime#80527) and the following code must be updated to add context to combine with the current one.

aspnetcore/src/Http/Http.Extensions/src/ProblemDetailsJsonOptionsSetup.cs

Lines 16 to 22 in e523876

	if (options.SerializerOptions.IsReadOnly)
	{
	options.SerializerOptions = new(options.SerializerOptions);
	}
	// Combine the current resolver with our internal problem details context
	options.SerializerOptions.TypeInfoResolver = JsonTypeInfoResolver.Combine(options.SerializerOptions.TypeInfoResolver!, ProblemDetailsJsonContext.Default);