Fix bug in calling of SomethingLike serialisation

When using SomethingLike in the body of the answer, there is a code creash. This fixes it.

No code spec demonstrating the issue, I did not figure out where these go. 
My sample is a high level one: 
      .will_respond_with(
          status: 200
          body: ({ login: "ok",
                  stuff: Pact::SomethingLike.new(10), #Pact::Term.new(generate: '10', matcher: /\d+/),
            }))