Log Message:
Update to 5.7.1. From the changelog:

- bug fix for reporter order: will preference VScode over diff
  command line.
- added VSCode Reporter, a reporter to launch a visual diff in VS Code,
  this requires code is accessible from the command line.
    - If you are using Gitpod in the browser, approvaltests will open a
      diff view in your browser.
- Fixes Python Native Reporter to be the default reporter; if no other
  reporters are found on your machine, PythonNative reporter will be
  used. This means that the approval tests library will print a diff on
  an unconfigured machine.