Bump python-telegram-bot from 20.5 to 20.6

Bumps [python-telegram-bot](https://github.com/python-telegram-bot/python-telegram-bot) from 20.5 to 20.6.
- [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/v20.5...v20.6)

---
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

@@ -7,7 +7,7 @@ ccxt==4.0.112
 cryptography==41.0.4
 aiohttp==3.8.5
 SQLAlchemy==2.0.21
-python-telegram-bot==20.5
+python-telegram-bot==20.6
 # can't be hard-pinned due to telegram-bot pinning httpx with ~
 httpx>=0.24.1
 arrow==1.3.0