libvmaf WARNING pkl model files have been deprecated, use json

[halkun]

Received the following error when trying to run.

Pass 1/2 frame 1/0 0B 0 us 0.00 fpm [ETA unknown] libvmaf WARNING could not read model from path: "tools\model\vmaf_v0.6.1.pkl"
libvmaf WARNING pkl model files have been deprecated, use json
Fatal error: Failed to load VMAF model.

Fixed by modifying line in the video.bat file:
Before:
--vmaf-model-path=tools\model\vmaf_v0.6.1.pkl ^

After:
--vmaf-model-path=tools\model\vmaf_v0.6.1.json ^

Root cause:
https://ci.appveyor.com/project/f11894/aom/build/artifacts only supplies vmaf_v0.6.1.json file now instead of vmaf_v0.6.1.pkl