[sdk] pin HuggingFaceHub Dependency (#1478)

[sdk] pin HuggingFaceHub Dependency

HuggingFace Hub Python library released breaking changes in version
0.22.0:
https://github.com/huggingface/huggingface_hub/releases/tag/v0.22.0

This diff pins the version dependency of `huggingface_hub` to avoid the
impact of the broken change.

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[//]: # (BEGIN SAPLING FOOTER)
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* #1479
* __->__ #1478

python/requirements.txt

@@ -6,7 +6,7 @@ flask-cors
 flask[async]
 frozendict
 google-generativeai>=0.3.1
-huggingface-hub >= 0.20.3
+huggingface-hub >= 0.20.3, <= 0.21.4
 hypothesis==6.91.0
 lastmile-utils==0.0.23
 nest_asyncio