convert scale_factors from list to array to prevent UserWarning

[austinmw]

Motivation

#7728

Modification

Wrap lists in np.array

[codecov]

Codecov Report

Merging #7937 (810573c) into master (73b4e65) will decrease coverage by 0.03%.
The diff coverage is 50.00%.

@@            Coverage Diff             @@
##           master    #7937      +/-   ##
==========================================
- Coverage   64.71%   64.68%   -0.04%     
==========================================
  Files         351      351              
  Lines       28461    28463       +2     
  Branches     4807     4807              
==========================================
- Hits        18418    18410       -8     
- Misses       9055     9066      +11     
+ Partials      988      987       -1     

Flag	Coverage Δ
unittests	64.68% <50.00%> (-0.03%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
mmdet/models/dense_heads/yolo_head.py	46.98% <50.00%> (+0.21%)	⬆️
mmdet/models/dense_heads/yolox_head.py	78.97% <50.00%> (+0.10%)	⬆️
mmdet/models/detectors/cornernet.py	94.87% <0.00%> (-5.13%)	⬇️
mmdet/core/post_processing/bbox_nms.py	74.62% <0.00%> (-4.48%)	⬇️
mmdet/models/dense_heads/corner_head.py	68.33% <0.00%> (-1.39%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 73b4e65...810573c. Read the comment docs.

[OpenMMLab-Assistant005]

Dear austinmw,
First of all, we want to express our gratitude for your significant PR in the MMDetection project. Your contribution is highly appreciated, and we are grateful for your efforts in helping improve this open-source project during your personal time. We believe that many developers will benefit from your PR.
If you are Chinese or have WeChat，welcome to join our community on WeChat. You can add our assistant ：openmmlabwx. Please add "mmsig + Github ID" as a remark when adding friends：）
We would also like to invite you to join our Special Interest Group (SIG) private channel on Discord, where you can share your experiences, ideas, and build connections with like-minded peers. To join the SIG channel, simply message moderator— OpenMMLab on Discord or briefly share your open-source contributions in the #introductions channel and we will assist you. We look forward to seeing you there! Join us ：https://discord.gg/raweFPmdzG
Thank you again for your contribution❤
Best regards！ @austinmw