“Live” previews doesn't follow changes of file system based external refs

[paulRbr]

With the live preview command bump preview --live if the provided definition uses file system based references, then those external references are not “watched” by the CLI.

E.g. openapi.yaml

paths:
  /v1/version:
    $ref: 'v1/version.yaml'

With a Path Item object of the /v1:version endpoint in the external file v1/version.yaml

Steps to reproduce

• Launch the live preview command bump preview --live --open openapi.yaml
• Change the v1/version.yaml file
• Nothing happens

What should happen

• Launch the live preview command bump preview --live --open openapi.yaml
• Change the v1/version.yaml file
• The preview should be updated with the latest file system changes