add python-amazon-paapi dependency

- Add python-amazon-paapi>=5.0.0 for Amazon Product Advertising API
- Required by htk.lib.amazon.api module

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Co-Authored-By: Claude <noreply@anthropic.com>

Author: jontsai

requirements.txt

@@ -6,6 +6,7 @@ emoji>=2.12.1,<3
 numpy>=1.26.0,<3
 pydantic>=1.10.13,<3
 pygeoip>=0.2.6,<1
+python-amazon-paapi>=5.0.0
 python-dateutil>=2.9.0,<3
 python-ulid[pydantic]>=2.4.0,<3
 redis>=4.4.4,<5