[STYLE] run autopep8 and isort (#421)

Run:
```
isort ./python
autopep8 -i --ignore E501,E701,E731 $(find ./python/ -name '*.py')
```
with an `.isort.cfg` and then clean up a few warts. This PR should be a no-op; the idea is that this is all boring whitespace changes, and any config file changes will be in a different change to make it easier to review.

python/triton/language/random.py

@@ -1,7 +1,6 @@
 import triton
 from . import core as tl
 
-
 PHILOX_KEY_A: tl.constexpr = -1640531527  # 0x9E3779B9
 PHILOX_KEY_B: tl.constexpr = -1150833019  # 0xBB67AE85
 PHILOX_ROUND_A: tl.constexpr = -766435501  # 0xD2511F53