Bump py17track to 2.1.1

[bachya]

Description:

This PR bumps py17track to 2.1.1. Changelog: https://github.com/bachya/py17track/releases/tag/2.1.1

This fixes an issue where the platform would incorrectly compare its current entity set to the incoming entity set and create sensors that already exist.

Related issue (if applicable): N/A

Pull request in home-assistant.io with documentation (if applicable): N/A

Example entry for configuration.yaml (if applicable):

sensor:
  - platform: seventeentrack
    username: !secret 17track_user
    password: !secret 17track_password

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.

If the code communicates with devices, web services, or third-party tools:

• New dependencies have been added to the REQUIREMENTS variable (example).
• New dependencies are only imported inside functions that use them (example).
• New or updated dependencies have been added to requirements_all.txt by running script/gen_requirements_all.py.