Backslash not working for directory location in CLI

[CorieW]

Environment info

firebase-tools: 13.34.0

Platform: Windows

Steps to reproduce

There may be an easier way to reproduce this, but this is what I was having trouble with:

1. Init a project with firebase init
2. Install a local extension firebase ext:install ..\extension-name\

However, this will work:

1. Init a project with firebase init
2. Install a local extension firebase ext:install ../extension-name/

Expected behavior

Finds the extension and installs

Actual behavior

Responds with:

Error: Unable to parse ..\firestore-bigquery-export\ as an extension ref.
Expected format is either publisherId/extensionId@version or publishers/publisherId/extensions/extensionId/versions/version. If you are referring to a local extension directory, please ensure the directory exists.