Turn on exact_dtype by default on test_sparse.py (#34489) (#34542)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/34542
Turn on exact_dtype by default on test_sparse.py (#34489)
Pull Request resolved: #34489
Test Plan:
```
python test/test_sparse.py
```
Imported from OSS
Differential Revision: D20369764
fbshipit-source-id: ade2434f77af8ae419bda653b4c46616c052a8b2
