Doesn't work on files outside the workspace

Hello, thanks for this extension. One problem is that it doesn't work on files outside of the workspace.

For instance, if my Git repo has multiple packages in it like this:

• packages/
  • my-server/
  • my-frontend/

If I open packages/my-server/ with VS Code, the Git panel in VS Code will also show changes from the other folders in the Git repo. So, if I see a file from packages/my-frontend/, gitdiffer will not open them. It will only open files from the workspace folder, packages/my-server/...