* Intermediate version
* Fix yaml template & Successfully run rolling
* Be compatible with benchmark
* Get same results with previous linear model
* Black formatting
* Update black
* Update the placeholder mechanism
* Update CI
* Update CI
* Upgrade Black
* Fix CI and simplify code
* Fix CI
* Move the data processing caching mechanism into utils.
* Adjusting DDG-DA
* Organize import
* Fix high-freq data name from `yahoo_cn_1min` to `cn_data_1min`
* re-format example data names using `qlib_{region}_{feq}`, e.g. qlib_cn_1d
* re-format example data names using `{region}_{feq}`, e.g. us_1d and cn_1min
* keep using for 1day data, and change 1min data to