Pin scipy to 1.6.3 on Windows and Mac (#64844)
Summary:
It's already pinned by via docker install on Linux
As `scipy.stats.`[`poission`|`geom`|`binom`] returns quite different results in 1.7+ versions of SciPy
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64844
Reviewed By: driazati
Differential Revision: D30876591
Pulled By: malfet
fbshipit-source-id: 4946e0922063e9ac320c218a0b089f73486466f7
