Bump python-telegram-bot from 13.15 to 20.3

Bumps [python-telegram-bot](https://github.com/python-telegram-bot/python-telegram-bot) from 13.15 to 20.3.
- [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](python-telegram-bot/python-telegram-bot@v13.15...v20.3)

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

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

requirements.txt

@@ -12,7 +12,7 @@ packaging==23.1
 prometheus-client==0.17.0
 pycron==3.0.0
 python-pushsafer==1.1
-python-telegram-bot==13.15
+python-telegram-bot==20.3
 pytz==2023.3
 pytz-deprecation-shim==0.1.0.post0
 requests==2.31.0