* added scripts for char-based lang prep training scripts
* added `Zipformer` recipe for commonvoice
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Co-authored-by: Fangjun Kuang <csukuangfj@gmail.com>
* fixes for `diagnostics`
Replace `2 ** 22` with `512` as the default value of `diagnostics.TensorDiagnosticOptions`
also black formatted some scripts
* fixed formatting issues