[bug] Dev server breaks when defining certs

[retlehs]

Describe the issue

https://bud.js.org/guides/general-use/dev-server#configuring-ssl

Passing cert and key to the dev server results in an error

Props to @daverobertson for bringing this to our attention

Expected Behavior

Dev session starts

Actual Behavior

TypeError 

Server is not a constructor

Steps To Reproduce

1. Configure a Bud project with certs

   .proxy('https://example.test')
    .serve({
      host: 'example.test',
      cert: app.path('/path/to/cert.crt'),
      key: app.path('/path/to/key.key'),
    })

version

6.6.7+