fix pytest.mark for testcase

Previously function op_select_format and check_supported raise an exception directly on the tbe_process python side, but we don't deal with the exception, and raise an exeception on c++ side to frontend ME, that will cause some conflict when recycle resource on ME and tbe_process python interpreter.
This changes adding try...catch in function op_select_format and check_supported on the python side, and return the Exception string to c++ side, so that we can raise an exception to frontend ME and ME will deal with resouce clearning and exit.

Signed-off-by: Ting Wang <kathy.wangting@huawei.com>

Signed-off-by: Ting Wang <kathy.wangting@huawei.com>

Signed-off-by: Jonathan Yan <jonathan.yan1@huawei.com>

1.Change dtype of scale to dtype of grad in loss_scale.py;
2.Change dtype of weight_decay to dtype of weight in optimizer.py.

Merge pull request !178 from Simson/rebuild-graph-before-RunGraph

Merge pull request !175 from Simson/rebuild-graph-before-RunGraph

Merge pull request !7 from JoyLvliang/ms-incubator-pynative-add-lenet

Merge pull request !82 from caifubi/dev-profiling

Merge pull request !156 from Xiaoda/implementing-memory-calculation-in-auto-parallel