Upgrade python-telegram-bot to 6.0.3

[fabaff]

6.0.3

• Changelog: https://github.com/python-telegram-bot/python-telegram-bot/commits/master

6.0.2

• Avoid confusion with user's urllib3 by renaming vendored urllib3 to ptb_urllib3

Tested with the following configuration:

telegram_bot:
  - platform: polling
    api_key: !secret telegram_api
    allowed_chat_ids:
      - !secret telegram_client

notify:
  - platform: telegram
    name: telegram
    chat_id: !secret telegram_client

Message sent with "Call Service"

{"message": "The sun is {% if is_state('sun.sun', 'above_horizon') %}up{% else %}down{% endif %}!"}

Thanks to #7877, it's working 😄

[mention-bot]

@fabaff, thanks for your PR! By analyzing the history of the files in this pull request, we identified @azogue, @balloob and @rmkraus to be potential reviewers.