feat: allow running review app to validate PR from external contribution

* configure buildpack to build poetry application

Procfile

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+web: streamsync edit apps/hello

requirements.txt

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+annotated-types==0.6.0 ; python_full_version >= "3.9.2" and python_version < "4.0"
+anyio==4.2.0 ; python_full_version >= "3.9.2" and python_version < "4.0"
+click==8.1.7 ; python_full_version >= "3.9.2" and python_version < "4.0"
+colorama==0.4.6 ; python_full_version >= "3.9.2" and python_version < "4.0" and platform_system == "Windows"
+exceptiongroup==1.2.0 ; python_full_version >= "3.9.2" and python_version < "3.11"
+fastapi==0.109.2 ; python_full_version >= "3.9.2" and python_version < "4.0"
+h11==0.14.0 ; python_full_version >= "3.9.2" and python_version < "4.0"
+idna==3.6 ; python_full_version >= "3.9.2" and python_version < "4.0"
+numpy==1.26.4 ; python_full_version >= "3.9.2" and python_version < "4.0"
+packaging==23.2 ; python_full_version >= "3.9.2" and python_version < "4.0"
+pandas==2.2.0 ; python_full_version >= "3.9.2" and python_version < "4.0"
+plotly==5.18.0 ; python_full_version >= "3.9.2" and python_version < "4.0"
+pyarrow==15.0.0 ; python_full_version >= "3.9.2" and python_version < "4.0"
+pydantic-core==2.16.2 ; python_full_version >= "3.9.2" and python_version < "4.0"
+pydantic==2.6.1 ; python_full_version >= "3.9.2" and python_version < "4.0"
+python-dateutil==2.8.2 ; python_full_version >= "3.9.2" and python_version < "4.0"
+pytz==2024.1 ; python_full_version >= "3.9.2" and python_version < "4.0"
+six==1.16.0 ; python_full_version >= "3.9.2" and python_version < "4.0"
+sniffio==1.3.0 ; python_full_version >= "3.9.2" and python_version < "4.0"
+starlette==0.36.3 ; python_full_version >= "3.9.2" and python_version < "4.0"
+tenacity==8.2.3 ; python_full_version >= "3.9.2" and python_version < "4.0"
+typing-extensions==4.9.0 ; python_full_version >= "3.9.2" and python_version < "4.0"
+tzdata==2023.4 ; python_full_version >= "3.9.2" and python_version < "4.0"
+uvicorn==0.27.0.post1 ; python_full_version >= "3.9.2" and python_version < "4.0"
+watchdog==3.0.0 ; python_full_version >= "3.9.2" and python_version < "4.0"
+websockets==12.0 ; python_full_version >= "3.9.2" and python_version < "4.0"