* rm retain grad

* fix zero_dim

* fix zero_dim for xpu

* reset zero dim for xpu

* reset xpu

* reset custom_relu

* Reset flip

* fix zero dim

* update config

* re-blacken python code

* temporarily disable date and diff_py_file

* skip a format

* [CodeStyle] remove all future import

* revert test_error.py

* restore future import in example code

* add sparse api coalesce

* fix to_sparse_csr

* use GpuMemcpy and GpuMemset

* sparse convert kernel support double dispatch by indices dtype

* cudaMemcpyKind->gpuMemcpyKind

* use yapf to format all python file

* yapf exclude two unittests file for they rely on writing and reading file, and format will break them

* disable diff_py_file because too many diff files cause command following failed

* [Eager] FLAGS_retain_grad set false

* Add FLAGS_retain_grad_ for some tests

* Add FLAGS_retain_grad_ to some tests

* modified set_flags

* modified set_flags

* fix windows-ci and windows-openblas-ci

* import paddle.fluid

* call sparse api from python