Update dependency python-telegram-bot to v21.8

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
python-telegram-bot (changelog)	21.7 -> 21.8

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Release Notes

python-telegram-bot/python-telegram-bot (python-telegram-bot)

v21.8

Compare Source

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Released 2024-12-01

This is the technical changelog for version 21.8. More elaborate release notes can be found in the news channel @pythontelegrambotchannel <https://t.me/pythontelegrambotchannel>_.

Major Changes

• Full Support for Bot API 8.0 (:pr:4568, :pr:4566 closes :issue:4567, :pr:4572, :pr:4571, :pr:4570, :pr:4576, :pr:4574)

Documentation Improvements

• Documentation Improvements (:pr:4565 by Snehashish06 <https://github.com/Snehashish06>_, :pr:4573)

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