`s2dm export vspec` crashes when working with float arguments in the `@range` directive

[ahmdmhd]

The @range directive is defined as follows:

directive @range(min: Float, max: Float) on FIELD_DEFINITION

However, the vspec exporter crashes, when it tries to deal with a float argument, with the following error:

ValueError: invalid literal for int() with base 10: '0.0'

Example GraphQL:

type Vehicle {
  Speed(unit: Velocity_Unit_Enum = KILOMETER_PER_HOUR): Float
    @range(min: 0.0, max: 500.0)
}