Add non-documented phone number verification IsValid allowed value

[lostie]

Loqate does not document that this is an allowed value for this property but it keeps returning responses with this value on it.

Dry::Types::ConstraintError: "Maybe" violates constraints (included_in?(["Yes", "No", "Unknown"], "Maybe") failed)

[lostie]

/cc @wilsonsilva for 👀

FYI, it seems the travis build error is related with this: jruby/jruby#6581

[lostie]

@wilsonsilva Thanks for reviewing!

It seems like:

• Travis does not yet support the jruby version that fixes the build issue (9.2.16 is required)
• the gemspec seems to be specific to the MRI version (spec.required_ruby_version = '>= 2.4.0').

Should we skip the jruby checks until both of those are addressed and they don't block the release of the new features?

[wilsonsilva]

@lostie Yeah, sounds good. Let's skip JRuby for the time being.