Use https instead of http in hello.py

[whitphx]

📚 Context

N/A

🧠 Description of Changes

https:// is preferable than http://. Same as https://github.com/streamlit/docs/pull/961/commits/3852cf406a08d079ea02b98012a0d4f82a8fd253

💥 Impact

Size:

• [x] Small
• [ ] Not small

🌐 References

N/A

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