* Update yolo.py

* Update export.py

* fix export grid

* Update export.py, remove detect export attribute

* rearrange if order

* remove --grid, default inplace=False

* rename exp_dynamic to onnx_dynamic, comment

* replace bs with 1 in anchor_grid[i] index 0

* Update export.py
Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>