fix python local template when artifact dirs are present

[asottile]

previously failing with:

    Processing /home/asottile/.cache/pre-commit/repo8k0clr83
      Installing build dependencies: started
      Installing build dependencies: finished with status 'done'
      Getting requirements to build wheel: started
      Getting requirements to build wheel: finished with status 'error'
stderr:
      error: subprocess-exited-with-error
      
      × Getting requirements to build wheel did not run successfully.
      │ exit code: 1
      ╰─> [14 lines of output]
          error: Multiple top-level packages discovered in a flat-layout: ['renv', 'target'].

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