* Use new APIs with k2.RaggedTensor * Fix style issues. * Update the installation doc, saying it requires at least k2 v1.7 * Use k2 v1.7
* Fix style and add copyright * Minor fix * Remove duplicate lines * Reformat conformer.py by black * Reformat code style with black. * Fix github workflows * Fix lhotse installation * Install icefall requirements * Update k2 version, remove lhotse from test workflow