[Bug] rfl::yaml::write Serialization Issue with Double Data

[m1dsolo]

Description

When using rfl::yaml::write to serialize a double, if the double's value is an integer, it gets serialized as an integer instead of a floating-point number.

auto obj = rfl::Generic::Object();
double age = 10;
obj["age"] = age;
auto s = rfl::yaml::write(obj);
std::cout << s << std::endl;  // age: 10   (expect: age: 10.0)

This leads to an error during deserialization:

s = "age: 10";
obj = rfl::yaml::read<rfl::Generic::Object>(s).value();
age = rfl::from_generic<double>(obj.get("age").value()).value();
// error is:
// terminate called after throwing an instance of 'std::runtime_error'
// what():  rfl::Generic: Could not cast the underlying value to a double.
// zsh: IOT instruction (core dumped)  ./build/xxx

JSON serialization does not exhibit this problem; it correctly serializes the value as {"age":10.0}.

Expected Behavior

The double value should be serialized as a floating-point number (e.g., "age: 10.0") in YAML, allowing for successful deserialization and extraction as a double.

Thank you for your efforts!

[liuzicheng1987]

OK, I will take a look.

[liuzicheng1987]

@m1dsolo , this PR should fix the issue. Thanks for reporting.