Bump python-telegram-bot from 20.7 to 20.8

Bumps [python-telegram-bot](https://github.com/python-telegram-bot/python-telegram-bot) from 20.7 to 20.8.
- [Release notes](https://github.com/python-telegram-bot/python-telegram-bot/releases)
- [Changelog](https://github.com/python-telegram-bot/python-telegram-bot/blob/master/CHANGES.rst)
- [Commits](https://github.com/python-telegram-bot/python-telegram-bot/compare/v20.7...v20.8)

---
updated-dependencies:
- dependency-name: python-telegram-bot
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

requirements.txt

@@ -6,7 +6,7 @@ ccxt==4.2.39
 cryptography==42.0.2
 aiohttp==3.9.3
 SQLAlchemy==2.0.25
-python-telegram-bot==20.7
+python-telegram-bot==20.8
 # can't be hard-pinned due to telegram-bot pinning httpx with ~
 httpx>=0.24.1
 arrow==1.3.0