fix: Update prepare to use format instead of test-format (#858)

`hatch run prepare` should prep all the files to ensure it's ready for a PR, so switch it to format files instead of testing the format. Otherwise it just quits with output of the files that need to be formatted

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Co-authored-by: Mackenzie Zastrow <zastrowm@users.noreply.github.com>
Co-authored-by: Nick Clegg <nac542@gmail.com>